I've never gotten the chance to fly on a 747, and always wanted to. I always wanted to splurge on a trip to Europe and fly in the upper deck of the 747. I see on a Wikipedia article (if accurate) that British Airways still flies 34 of them, and Virgin Atlantic flies 8. So maybe there's still a chance for me to hop a ride on one before they totally disappear from service.
I've flown on the 747 exactly five times; to/from Sydney in an AirNZ 747-400; Qantas DFW-Melbourne and Sydney-DFW (they couldn't *quite* make DFW-SYD, so the westbound flight was to MEL; resolved now by having the route covered by the A380); and last year, DFW-LHR on BA.
On the last, we splurged and bought business class, upper deck. It was very nice, only five rows of four seats, so uncrowded and excellent service, plus (of course) got to visit the cockpit briefly prior to departure. The entertainment system was Flintstones era, but it worked. No wifi. Plus, being upstairs, the cabin layout meant you had lots of spread-out room at the windows.
Really enjoyed the experience; only real discordant note is that, on British, after you pay five grand to buy the business class trip ("Club World"?), you still have to pay additional money to select your seat before 24 hours prior to departure... and extra $140 or so to ensure we got seated upstairs.