Longest trip
I've done Providence, RI (Atlantic coast) to San Diego, CA (Pacific coast) and back in a C150. Took me 75 flying hours -- obviously, a lot faster on the way back than the way out, given the prevailing westerlies.
I don't fly longer legs than three hours, because the fuel gauges are crap, and GPH varies with atmospheric conditions. Thinking of putting in an EI fuel monitor, which would tell me to a high degree of accuracy how much I've burned, and might make me more comfortable about extending that three-hour range a bit.