Last spring, I flew to Germany to reunite with my husband after his military deployment. We splurged on an upgrade to the most premium class available for our flight home, spending an extra $699 each for Delta One.

The lie-flat seat was a luxury on our 10-hour flight, and the service was fantastic, but our plane seemed a bit outdated and worn. From the clunky entertainment system to the lack of privacy between seats, I felt our nearly-20-year-old aircraft showed its age.

We got elevated meals, amenity kits, and complimentary alcohol, but I expected more features or perks considering a Delta One upgrade often costs thousands of dollars.

Although our experience fell short of my expectations, I still think the upgrade was worth paying for to celebrate such a special occasion.

In the future, I would only justify the cost of Delta One if I knew I'd be on a newer plane with more state-of-the-art amenities. After all, some newer Delta One classes have suites with doors.

When returning from Europe last winter, my husband and I upgraded to Premium Select seats for $209 each on our nine-hour flight.

Premium Select upgrades are primarily offered on long-haul flights and come with early boarding (although my status already gets me into the same boarding group that this would).

We enjoyed the added legroom and additional recline of our seats, which made them noticeably more comfortable. The upgraded dining, larger entertainment screens, and in-flight amenity kits also elevated the experience.

However, we upgraded at the last minute, so our seat options were limited. Unfortunately, I ended up sandwiched in the middle seat next to a stranger. In hindsight, I wish I'd saved the money and kept my window seat in economy.

Being crammed in a middle seat for nine hours took away from the premium experience. Next time, I'd try to upgrade earlier so I could choose a better seat.

Overall, Premium Select strikes a solid balance between affordability and comfort with its thoughtful amenities and extra space. However, it's not always available on Delta flights, and I'd likely skip it if I couldn't get a spot next to a window.

A step above economy, Delta's Comfort Plus provides slightly more legroom and priority boarding. For domestic itineraries, this class also receives alcoholic drinks and a better selection of snacks.

With my status, I've received many complimentary upgrades to Comfort Plus.

Last fall, I flew in Comfort Plus from Seoul to Atlanta after one such free upgrade. As a tall woman, the extra legroom was an added bonus, especially on a 13-hour flight.

However, I've found you can get about the same amount of legroom in an economy exit row for a more affordable price.

I'm happy to accept a free upgrade to Comfort Plus, but I wouldn't pay extra for these seats, which I've seen cost $100 or more than economy.

And, on international routes, Comfort Plus receives many of the same in-flight amenities as the rest of the main cabin. That said, Comfort Plus does get reserved overhead bin space, which is always nice on a fully booked flight.

Most of my Delta flights have been in economy class, including long-haul flights to Africa, Europe, Asia, and Australia.

Although some complain about economy seats, I actually prefer choosing this affordable option. For starters, Delta's main cabin offers more seat choices, which gives me flexibility.

I can almost always snag my preferred seat next to a window, where I can lean on the side of the plane to sleep during the flight.

Plus, I often monitor the seating chart before international flights, and like that I can move near an empty row or seat whenever possible.

Although some also consider basic economy to be a cabin category, its seats are still in the main cabin, you just can't choose where you sit (and there are limitations with changing and canceling your trip).

I'd rather be able to select my seat before my flight instead of saving a few bucks.

Overall, I'd rather book a cheaper flight so I can spend money elsewhere on my trip.

A flight is just one of the many costs of a vacation. I also need to pay for accommodations, additional transportation, meals, and activities.

By booking affordable economy flights, I have more money to travel more often — and that's always my goal. Plus, I can almost always secure my beloved window seat if I book my trip far enough in advance.

However, I'm definitely still open to enjoying the occasional upgrade if the price, plane, and time feel right.

I flew from NYC's LaGuardia Airport to Denver International Airport with United Airlines. My $165 basic economy ticket didn't include carry-on luggage or a seat selection. I paid an additional $40 to check my bag, so, in total, I paid $205 for this flight.

I arrived at the airport about an hour before 10 a.m. takeoff and got my seat assignment when I checked in.

The flight had 166 seats and in-seat power for rows one through 21, but I couldn't access an outlet since I was seated closer toward the back.

While my flight back was on Delta's Airbus A321neo, the airline says its Boeing 737-800 fleet has 160 seats, all with power outlets.

My seat was between 16 and 17 inches wide with a 30-inch seat pitch. With passengers on either side of me, I felt cramped in the small space, and even at 5-foot-3, there wasn't enough leg room for comfort.

The seats on Delta's Boeing 737-800 are slightly larger, with an inch wider seat pitch.

United Airlines told Business Insider that a new aircraft with upgraded interiors and more overhead bin space was coming soon as part of the United Next initiative.

There was a seat-back entertainment screen in front of me with access to DirecTV. I could have used my phone to access a library of shows and movies with the United app, but I didn't want to watch on a small screen.

I sampled the cable offerings, but there wasn't much to watch. The remote on my armrest was sticky, and I found it tough to push the buttons — especially when the passenger next to me was resting their arm on it.

United told BI that the upgraded United Next interiors would have touchscreen entertainment systems, Bluetooth connectivity, and power outlets at every seat.

Delta began refreshing its Boeing 737-800 fleet in January with more seatback entertainment options, and some are already in service.

It had a modern faucet, too.

I booked my basic economy flight from Salt Lake City to NYC with Delta. The $175 ticket included one carry-on bag but no seat assignment.

I arrived at Salt Lake City International Airport about an hour before my original 5:35 p.m. flight to Newark Liberty International Airport in New Jersey. When I checked in, I learned I'd get my seat assignment at the gate.

Once past security, I stood in line at the gate for my seat assignment. I overheard the attendant on the phone saying the flight was overbooked and another flight to John F. Kennedy International Airport was leaving 10 minutes later with plenty of empty seats.

JFK is much closer to my NYC apartment than Newark, so I told the attendant I'd be happy to switch flights. She thanked me and gave me a new boarding pass for the 5:45 p.m. flight.

The plane, which could seat 194 passengers, had many empty seats, and I was lucky enough to land a row to myself.

The seats were 1 inch wider and felt cushier than the ones on United. I was also surprised that a 1-inch wider seat pitch made a huge difference in legroom.

United's Airbus A321neo has a couple more rows of seats than Delta's, and the seats are a bit smaller and have one less inch of legroom.

The entertainment screen in front of me showed hundreds of movies and TV shows, from Blockbuster hits to independent films. I also had access to a power outlet to charge my phone.

The fixtures looked slightly less modern than those on the United flight.

From the included carry-on bag to the more comfortable seats with additional entertainment and amenities, Delta's basic economy felt much more comfortable for $30 less.