Concorde-Duh
707 series-only seen one or two cargo ones, and they have such an important place in history it is a shame we can't fly on them anymore.
DeHavilland Comet- Its beautiful, and though not an earth-shaker like the 707, t was the first.
Convair 990-Don't know much about it, but something about this aircraft captivates me.
747SP- Seen one only once, would love to go for a ride on it.
Lockheed Constellation-my god, what a plane
Military:
XB-70- Beautiful, big, and fast... dwarfs Concorde and faster too!
B-58 Hustler-Big, bad bomber.
B-36 Peacemaker- six pushing props, four jets, and wingspan that dwarfs the 747. Nuff said.
B-29- Historic aircraft... to my knowledge, only one is still airworthy.
SR-71/A-12/YF-12-Any or all of these would make my day!
And, probably above all, the Boeing 314 Clipper. That thing has got to be the most majestic aircraft ever built. It's the transition from sea to air, and opened up routes though impossible. The fact none exist anymore (I think) is tragic. When I make my first billion, expect to see a new one

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Edit-added Connie
[Edited 2004-01-21 19:07:45]