I fly a lot. I abide by these two rules: The space under your seat belongs to the passenger behind you. The space in front of you is fully yours, up to the farthest point back that the passenger in front of you can recline their seat.
You can use it while they don't recline, but it's theirs if they choose to use it. It has sometimes limited the angle on my laptop but that's what you get if you don't opt for first class.
I'm so glad I'm not forced to get on one of those sardine deathtraps. Last time I flew I was packed in next to some guy and he was basically sitting on my lap. And I'm supposed to pay $500 for that? No thanks.
I refuse to sit in a middle seat, when flying with my husband. As a matter of fact, I refuse to sit next to my husband, at all, because his shoulders are too broad for the seats, and if you get between two men with broad shoulders, you have to put your seat back to get enough room.
I had the window seat on the last row on a Southwest flight. My seat was against the back bulkhead and it would NOT recline. The seat in front of me was defective and reclined way too far backward. As soon as were were off the ground the b*tch in front of me tipped back and the back of her seat was 6 or 8 inches from my face. I asked her several times to move it back up but she ignored me. Did I mention that I am claustrophobic? I came boiling out of the seat and crawled across my husband and the young service man in the aisle seat. the stewardess came running up to tell me I HAD to sit down. Long story short, my husband is not claustrophobic so he too my seat and kicked the b*tch all the way to Denver about every 30 seconds. The reason I know she was a b*tch was because she never put her seat up and the stew never asked her to put it up. The good news is I know the b*tch didn't sleep a wink.
A few weeks ago, I flew a tiny commuter plane into La Guardia. I barely fit - and I am not exactly the biggest guy to walk into the room.
I'm so glad I have no need to fly any longer.