Seat assignments, even when family travel is not involved, are often the most important factors in making or breaking a trip. On a short flight it may not matter, but spending several hours in discomfort is no fun for anyone.

Someone has to sit in those middle seats, but here are six tips to assure it’s not you.

1. Choose a flight with decent available seats to preassign. This one may sound too obvious, but as a travel agent I routinely deal with travelers who care deeply about where they sit, but will choose a slightly earlier or later flight with no preassignable seats, over a flight that does have available seats. They seem to figure something will open up or they will be able to work it out at the airport.

As an agent, I’ll keep checking back for a good client; and, anyone who books directly can keep checking on their own. But, it’s not a guarantee. I’m not suggesting travelers alter a flight time by several hours. However, often a small change will yield good options, especially if you are flexible with airlines.

2. If Southwest Airlines flies the route you want, book them and pay the relatively small early boarding fee. While the most expensive “Business Select” travelers usually get exit rows, being in the regular early boarding group should guarantee, at the very least, an aisle or window.

3. Consider paying premium seat fees. In some cases, premium seats are actually better seats — as with United’s Economy Plus. In others, it may just be a so-called premium location. (Yes, it’s annoying just to pay for a regular seat towards the front of the plane, but at least it eliminates the worry.)

4. Some travel agents have special arrangements with airlines for preferred seat assignments. My agency, for example, has several such contracts. Find one of those agents.

There will be a ticketing fee and, in some cases, an additional fee because of the extra work, but it will still be less expensive than paying the premium seat fee yourself.

5. Once you have seat assignments, double check them. Check back at least a week before departure and again the day before. Also, check your seats ANY time there is a schedule change.

For an example, on a trip I booked with my husband in March, United changed the return flight time by only 15 minutes. Even though the aircraft was the same, our seats, when I checked online, had disappeared. Fortunately, I was able to grab the same seats back, but they wouldn’t have been there for long.

6. Check in on time. And, get to the gate on time. Advance boarding passes help. But when the airlines say, “Be in the boarding area 30 minutes prior,” they mean it. They can and do give seats away.

Personally, when I have checked bags, I often reprint my boarding pass at the airport, just to make sure my seat assignment hasn’t changed. (Several times in the past year it has.)

I’ve seen many, many travelers yelling at the poor gate agents claiming they’ve had seats for months or paid extra for seats, and those seats are now gone. Once the computer decides someone has missed the cut off, there’s not much that can be done.

In addition, if there are any last minute aircraft changes, be in the gate area before the last minute. You don’t want to have done a lot of work to get the right seat and still end up losing it.