^Depends on what kind of flight you are on too. From what I heard, on some flights they put your luggage on the next flight if yours is full.
Here are some tips that I found:
- If you arrive at the counter to check in ask them if they have any upgrades. Usually they will tell you "oh yes, we have last minute upgrades (LMU) for $XXX.XX". Sometimes those prices are actually worth it, other times you think "fkkkuuuuuuuuuu~". Now, if you arrive to check in fairly late, I am not sure if they will give you the upgrade, but I heard that sometimes if the plane is fairly full and you are traveling internationally or on a larger plane, they will sometimes bump you up in order to accommodate a new customer who wants to get on as Economy. Chances of this is low, but I mean, if you look like Brad Pitt and the agent is jizzing over you then you may have a higher chance.
- There is also a chance to do the above at the gate, like before, if you are the gate, you might get a chance to get upgraded in order for the airline to accommodate a person on the economy reserve list. Chances again, are low, but a chance is a chance! The downfall of arriving late in both scenarios is that you will not get an overhead compartment space near your seat which is a big bitch to handle, and also, you cause everyone to get up for you to get to your seat (unless you sit aisle).
- I was fortunate to get upgraded once, no idea how, but I was very young and it was probably cause I was kawaii as fuck.
- Good way to check your seats and if they are good or not is using
Airline Seat Maps, Flights shopping and Flight information- Best Airplane Seats - SeatGuru and searching your airline and plane. It will give you a layout of the seats and which one have more leg room, which ones suck, etc. I used this site to realize my agent put me in fucked up seats with lesser legroom and no window so its very helpful to make sure you don't get jewed.
Edit: @lowside67, true, a lot of them are fairly dated or have different versions of the aircraft, you may need to guesstimate your plane etc.
-Another thing I heard is that if you have a larger person sitting next to you then, before the plane takes off etc, you can go talk to the attendants near the front or wherever private, and say that you are uncomfortable in your seating due to the person next to you. I think it was coined POS - Person of Size, and you can try to request another seat. If they don't have any they MAY upgrade you, I would test my luck on that one though, especially when you might have to sit uncomfortably for X hours.