I flew Delta One on a 9-hour overseas flight. Here's what surprised me about the business class seat.

When I flew Delta One out of JFK in February, I was ushered into a closed-off area of the airport for check-in. Attentive Delta agents checked my bags for me, offered me water while I waited, and escorted me through a private security line.

That check-in process differs based on the airport or country you're flying out of, and because I was flying Delta One from an international airport this time around, it wasn't as specialized as it had been at JFK. Like every other passenger, I carried my luggage to the departures lobby, where I spotted a Delta counter. Delta One and Sky Priority passengers shared a line, and it was not noticeably faster than any of the others nearby.

The staffer checking me in also appeared to work for the airport, not Delta, as she had to flag down a Delta agent to double-check something on my ticket. She was helpful, but she didn't seem to give me any extra attention because of my high-end ticket.

The bag check process took about 15 minutes, and I appreciated that my ticket allowed me to check two bags for free.

I then went through the same security line as everyone else at the airport, which was efficient but run-of-the-mill. As I walked out of the security area, I didn't feel like my Delta One ticket had made much of a difference in my travel experience yet.

At JFK, I visited the Delta One lounge, which is by far the most luxurious airport lounge I've ever been inside. However, Delta One lounges are only available at a few airports in the US, so when you're traveling internationally, a business class ticket will get you access to partner lounges instead.

My terminal at the Brussels airport featured The View lounge, an airy space with a plethora of cushy chairs, a huge breakfast buffet, a quiet library, and a bar with self-serve soft drinks and alcohol. If your ticket doesn't give you automatic entry, you can also purchase a day pass to The View for around $55.

I felt pampered in the lounge, where I grabbed a latte from one of several coffee machines and enjoyed a filling breakfast. There was even a chef making custom omelets for guests.

Lounge access was a huge perk of my Delta One ticket, especially because my flight ended up being delayed over an hour. It was much more relaxing to sit in the quiet lounge than to try to find somewhere to sit at my gate.

When it was finally time to board the plane, I couldn't wait to see my seat. I knew it would have a pillow and lie-down capabilities, but I was excited to see what other amenities it offered.

I wasn't disappointed. In addition to allowing me to lie down, the seat had a massage function to offer extra comfort. It also featured a cubby for my shoes, which I took advantage of immediately so I could wear the slippers Delta provided.

I also loved the headphones and care kit the airline provided. The kit included an eye mask, earplugs, socks, and toiletries like a toothbrush and hand cream.

In my opinion, the biggest benefit of flying Delta One is that the seat lies flat, making it easier to sleep on a long flight.

The reclining seat would have been plenty for me, but I was delighted to discover that Delta also provides a mattress pad for customers flying Delta One.

When you first sit down, the pad appears to be a lumbar pillow, but you can unroll it to create a mattress pad for extra comfort. I used the pad for nearly half the flight, loving the additional layer when I was watching a movie or trying to sleep.

When I've flown economy or in the main cabin in the past, I often haven't been able to see the first few rows of the plane, as flight attendants typically close the curtain that divides business class from the rest of the plane.

On my flight to Atlanta, though, the curtains were open for the duration of the journey, which I didn't mind. It was quiet on the whole plane for much of the journey as people tried to sleep, and if I wanted silence, I could pop the provided earplugs into my ears.

Plus, my husband was sitting in economy (he joined me on my work trip on our dime, so we weren't able to swing a Delta One ticket for him), and I liked that the open curtain allowed us to visit each other during the flight.

I hadn't given much thought to how the plane's cooling system might differ between the Delta One cabin and the rest of the aircraft.

To my surprise, it felt cooler at the front of the plane. I had two personal air filters above my seat, when I only expected one.

The air also apparently flowed better in Delta One than in the rest of the plane. While we were waiting on the tarmac, a flight attendant announced that they were adjusting the air to better cool the rear of the plane, where there were more passengers. My husband confirmed it had gotten pretty stuffy in the back of the plane.

At the time, my air was flowing so well that I had been planning to pull out my provided comforter for additional warmth.

I had a feeling I would be impressed by the food in Delta One, and the meal I had was certainly tastier than other airplane food I've eaten.

I was more impressed, though, by the way the flight attendants elevated the dining experience in Delta One.

Before they started serving food, a flight attendant spread out a cloth napkin on my tray table to keep the space clean. Everything was served in ceramic dishware, and the food was spaced out in courses, making me feel like I was in a restaurant.

Small touches like salt and pepper in a small shaker or a bottle of salad dressing instead of a packet also made the meal feel more luxurious.

A warm cookie brought to me on a plate was my favorite part.

After dinner, I tried to sleep, snuggling into my mattress pad with a comforter and pillow. I also used the eye mask and earplugs.

When I've fallen asleep on planes in the past, I've missed out on services from flight attendants, and I assumed that would be the case in Delta One as well (I intentionally stayed awake until warm cookies were served).

However, the flight attendants ensured I got to enjoy Delta One's amenities even if I snoozed. When I took off my eye mask toward the end of the flight, I saw that a flight attendant had left a hot towel for me on my side table rather than just skipping me when the service was provided.

It was a little touch, but it made me feel like the staff was considering my experience on the flight every step of the way.

I've always had difficulty sleeping on planes, but I was hopeful that my lie-flat seat might make it easier.

To my disappointment, I only slept for about two hours of my nine-hour flight, which was the same amount of time I slept on the journey to Europe when I was sitting in economy.

The seat was comfortable, but other passengers and flight attendants moving around and the bumps of occasional turbulence kept me awake. It was still lovely to stretch my legs out and relax, even if sleep eluded me.

I was so excited to fly Delta One that I had no nerves about flying for nine hours. But the journey from Brussels to New York was actually one of the worst travel experiences of my life.

My 10:45 a.m. CET flight was first delayed about 90 minutes because the incoming flight was late. Once we boarded, we sat on the tarmac for four hours before taking off for the nine-hour flight because of a mechanical problem. I wasn't able to get on a connecting flight to New York until 11 p.m. ET, so I wasn't home until after 2 a.m. I ended up traveling for a full 24 hours before I made it home.

Delta One made some of those stressors easier, as I was served additional snacks and beverages during the long wait on the tarmac, and I wasn't cramped in my seat, like some other passengers on the plane might have felt. It still wasn't fun to wait for so long, though, especially before a lengthy flight.

Sitting in business class didn't mean the experience on board was perfect either. For instance, mine and several other passengers' TV screens weren't working when we boarded, and the flight attendants weren't able to fix them with a hard reset until we had been on the plane for over six hours. It wasn't anyone's fault, but it did make the lengthy time on the flight less fun.

"Delta people have the autonomy to offer on-the-spot service recovery in the uncommon event of inoperative in-flight entertainment or Wi-Fi," a spokesperson for Delta told Business Insider when contacted for this story. "Of course, customers can further contact Delta to have additional concerns heard and additional compensation may arrive on a case-by-case basis."

Delta One offers a standout flight experience, but I'm glad I know now it won't make flying perfect.