A few years ago, I flew coach on United from San Francisco to Singapore. The flight is over 8,000 miles one way and takes over 18 hours (I had a stopover in Hong Kong).

It had been a long time since I flew such a long flight in coach, and it was one of the most miserable experiences I ever had traveling. To make matters worse, because it was a very full flight and I booked relatively late, I got stuck in a middle seat.

As it turned out, the man sitting in front of me liked to recline. For pretty much the whole trip (even during meal service). Every time he chose to recline his seat, he never bothered to check behind his seat, and would slam his chair back… right into my forehead. Worst of all, there was so little room from the end of my seat to the back of his, that once he would recline his seat, there was no way for me to get to my carry-on by my feet without putting my head in my seatmates’ laps (both strangers, by the way). My only salvation came on my right side—the elderly woman weighed barely 100 pounds and she was traveling with her equally elderly husband, who weighed about the same. They clung to each other for most of the flight and would get up to take breaks and use the restrooms at the same time, which meant I had elbow room on my right, as well as clear access to the aisle and to my bag. Unfortunately they had very large bladders and they only got up about every 4 hours.

Choosing a good seat can be its own science, and one Web site you should bookmark to make the task easier for you is SeatGuru.com.

Seatguru.com, founded in 2001 as a way to share information about airline seats.

SeatGuru is ingenious in its simplicity and practical application. It lists all major air carriers, and you can scroll down to find the various aircraft models they use. Select the particular aircraft your flight will likely be on, and voila—You see a seating diagram!

A sample seating diagram from SeatGuru.com.

Of particular interest for those who are traveling with just their carry-on is that SeatGuru tells you if there is no overhead bin or underseat space for your bag.

The site offers much more information, however. For example, what exactly is “seat pitch,” how does it differ from legroom, and why is it important for you? Why would a bulkhead seat work for some (more legroom) and not for others (no underseat storage space)? The site even helps you find out how to figure out what aircraft you are likely going to be flying for your flight.

Even if you use an online reservation system to book your flights, don’t just rely on the seating diagram the system offers you when you select your seat. Open a second browser window and find out exactly what you are signing up for.

Here are just a couple of things I consider when selecting a seat:

• An aisle seat doesn’t always work for me if I plan to stow my main carry-on under the seat in front of me, since there is an intrusive reinforcement bar that sticks down some inches in from the aisle, effectively narrowing the unblocked space I have by about 4 or 5 inches. If I choose an aisle seat, I have to be prepared to stick my carry-on in the overhead bin.
• Bulkhead seats are nice for the long-legged, but don’t really work if it’s important for you to stake out the overhead bin space for your carry-on. You will have to intrude into someone else’s overhead space (although at this time, airlines do not reserve that space for the seats below).

If you manage to pack absolutely everything into your carry-on bag but you still plan on accessing some of your belongings during the trip, you need to make yourself a little ditty bag to hold those items. Sometimes it’s as easy as using a one-gallon Ziploc resealable bag, although you can use any other lightweight bag. Pack whatever you might want to use during your flight, such as:

• Reading material, puzzle books, magazines
• Reading glasses
• Some snacks
• Ear plugs
• Eye mask
• Travel journal/diary
• Writing instrument
• Personal headset (and MP3 player like an iPod)
• Inflatable neck pillow

In addition, you might want to bring out your toiletry bag so that you can access your lotion, eye drops, and so on. The idea is to minimize your need for reaching up and dragging your carry-on bag, since you might not be in a good position to do so. If you keep all of your in-flight needs in one place, you can quickly slip it out as you are getting settled in your seat. You will likely be able to just put this in the seatback pocket in front of you (especially if it’s a plastic baggie, as it will slide around and possibly out of your reach).

The idea is to try to make your small environment as comfortable as possible, especially for a longer flight. Instead of listening to the same music loop over and over again, consider downloading a bunch of podcasts (I personally love the tales from NPR’s This American Life, and those shows are all an hour long), or listening to an unabridged book on CD (you could even download one from sites like Audible.com, or copy it into your MP3 player so you don’t have to lug a portable CD player around).

Had I had such a small seat pack with me on that flight to Singapore (instead of stashing everything in that unreachable bag by my feet), I wouldn’t have been so miserable for most of that flight.

I wound up having to take another business trip to Singapore the following year. For that trip, I made sure to get a seat in their (slightly more) roomier Economy Plus seat (with an added 3 inches of pitch! Woot…).