And you can walk right up to one at the museum at Hill Air Force Base in Layton, UT. (Probably other museums, too).
As a youngster, I got to see the XB-70 Vakyrie while at Hill AFB.
Edwards AFB has one accessible as well. Palmdale Air Park has an F117, SR, U2 and a boatload of other aircraft and still growing.
SZ
The Blackbird was truly in a class by itself.
Other Blackbirds:
AF museum in Dayton OH also has a XB-70 and many other aircraft and missiles. An astounding resource.
Blackbird Air park in Palmdale Ca (avenue P and 25th street east) also has F-117, A-12 (precursor to SR-71) and a nice selection of other aircraft.