GA: An Extra 300 would be fun.
Business: Tough choice... Probably a Citation X. Looks decent, goes fast, fair amount of room
Airliner: Tu-144! Amazing plane!
WWI: Fokker Dr.I! Who wouldn't want to think of themselves as the Red Baron?
WWII: Really tough choice here. It'd come down to the FW-190, P-38, P-47 F4U, or Me-262. More leaning towards the FW-190, P-38 or F4U.
Cold War: F-86. No questions!
Vietnam: F-104, F-8, or MiG-21!
Post-Nam: SR-71, F-16, A-10, F-15, Su-27, Su-35, Su-37, Su-47, MiG-29, MiG-35, MiG-31, Etc
Oh, and a C-17 would be pretty nifty too...
4GB DDR2 PC5300; 3.2GHz Pentium D 940, Nvidia 9800GT 1024MB DDR3, Windows XP Pro SP3