I love to travel but I do get claustrophobic on flights and have previously suffered panic attacks. The window seat definitely helps - I've had people question why as it's less "open" than an aisle but I find that I need to see outside and particularly when we are coming into land, need to track where we are, how far from the ground etc. I don't have a specific seat in mind - the cheaper the better. Don't care if I'm near the front or not; don't want any extra legroom (especially if by the emergency exit - far too much responsibility) so I'm probably not a prime candidate for a move but it did happen once - cabin crew approached DH and me to say that a family were scattered around and as we were two grown adults, we could probably sit apart. DH is a complete people pleaser and jumped up to move before I could respond - it was only when he looked back and saw my reaction that the consequences dawned on him. Needless to say, I had a panic attack, ended up on oxygen and DH moved back, much to the displeasure of the family who spent the rest of the flight loudly complaining that I'd been faking it.
These days, I board the aircraft ready to stand my ground. I'll happily move if DH and I can move and remain together and retain a window seat. At a push, if it's a visibly desperate situation involving an emergency, disabilities or a very young child with no other options, I'll forgo the window seat but absolutely need to stay with DH. For that reason, I wouldn't even consider taking a flight without prebooked seats and, emergencies aside, resent those who try to save a few bob at the expense of other travelers. My DSis is one of those - never pays to book seats because she knows that the crew won't separate her from her young child and "it will all work out".