In the little 'puddle jumpers' the wings aren't that long to begin with, as fuel tanks etc do not need to be huge as in larger passenger planes. I would be amazed to see any wing flex 29 feet! (Just watching Dick Ruttan's Voyager flex on the runway was amazing)
I've slept in my share of large planes at altitude (noisy beasts), but nothing makes you feel like you're 'flying' than simply cruising around at 130 knots atl 1000 feet. Its just as much fun to watch trainers (T-3 and T6), C-130's, and A-10 Warthogs at the AF base cruising around. Every one in a while we'd see a C5, and it was always a thrill to hear a plane taking off with JATO cannisters (they're loud!)
The ones that would always get us were the Blackhawk's coming over at 80-100' in the darkness, as the para-rescue trained. I didn't know him, but Jason Cunningham was one of the 1st casualties in Afghanistan (4 Mar 2002) attempting a rescue and had probably flew over us a thousand times. Ever since then a chill runs down my spine when I hear one in the darkness.
In that 29 feet flexing, I meant, that Boeing deliberately bent the wing on the 747 with cable pulleys and weights to see how far the wing will flex before it snapped, and the wing ( stress test ) flexed up at 29 feet before it broke.