I always select an aisle if I can and I have no issue getting up for the middle/window passengers. A small nudge is all that is needed if I'm asleep. I have always been fascinated when my middle/window companions on long-haul flights seem to manage without ever getting up (I'm talking 10+ hour flights... if you don't drink at least 2 litres of water on these flights I don't know how you survive), but I certainly wouldn't want anyone to put themselves into discomfort on account of not disturbing me.

On the occasions when I do not have an aisle, I try to avoid getting up more than is necessary to use the toilet but that's still going to be 2-3 times on a 10-hour flight. I will wait if the aisle passenger is sleeping but I've seen people sleep for 5+ hours, through meal service, and at a certain point I really can't wait any longer.