I have flown many redeyes, but most of them were shorter than transcon (a ton of SAN-ORD overnights, quite a few LAX-ORD, and LAX-DFW once or twice). I have also flown full transcons on a number of occasions, mostly LAX-JFK, but once on SJC-BOS. The flights are pretty good. In coach, American serves a light meal, usually a hot sandwich with chips and cookies or something similar. I have done the transcon redeyes in 767s, DC-10s, and a 757. The only time I really wasted the day afterward sleeping was on one particularly busy weekend... I had just graduated high school and attended our HS Grad night party that goes till 5 am. Headed straight to the airport and spent the day on a SAN-ORD flight that was delayed pretty significantly in flight for weather (it ended up taking about 8-9 hours after taking off), spent a day at Purdue to register for classes, flew to NY for a wedding, returned JFK-LAX with my family, who then flew down homt to San Diego while I met a friend and headed back to JFK on an overnight flight. When I finally arrived in NY for my vacation there, I was dead tired, but it was mostly because of the busy week rather than the flight itself.