I'm flying to Belgium from Seattle shortly before April 29th for hip surgery and need to stay until at least May 10th. My total budget for flight is $1500, and I'm worried about leg room on the way back after surgery.

Coach looks like it's going to cost just under $600 (my dates are somewhat flexible, the surgery is on April 29), but business class is around $4000, which is way more than I can afford.

I don't have any miles to use for an upgrade, but I've heard that an upgrade can sometimes be purchased at the gate. Is this even remotely possibly? What airlines should I consider? Should I just suck it up and ask the docs for more pain medication for the ride home? This is my first flight to Europe, so I don't know what to expect.

I've always booked my own flights for travel in the states, but perhaps I should consider calling a travel agent this time? If you experienced travelers have any tips for flying more comfortably, I'd be happy to hear them! (Also, any info on Ghent would be welcomed).