This list I made a while back for an old thread...
There are lots around the place wherever you go.
Some of my favourites I have visited are -
USA
Smithsonian Air and Space and Udvar Hazy in Washington DC - most famous planes/rockets ever flown
Intrepid Aircraft Carrier in New York - carrier type planes, concorde and space shuttle
Both NASA's - rockets
Ellsworth AFB South Dakota, B52's, B1 Bombers and Nuke missile silos nearby as well.
Pearl Harbour - Hawaii
Yorktown Aircraft Carrier - like Intrepid, not as well kept but can wander anywhere
UK
Duxford - UK planes, have flown into here on a light plane, the new American plane wing is now open again
Hendon - like Duxford older mainly UK planes
Yorkshire Aviation Museum is still set up like a WW2 bomber base, intact Halifax Bomber you can go inside
East Kirkby - Functioning Lancaster Bomber, taxi rides only - not flying
RAF Scampton - Dambusters Museum, Red Arrows...though I think they were moving?
RAF Cosford - excess planes from other museums
RNAS Yeovilton - UK naval aviation
Many ex WW2 stations have some remains or museums and light aircraft runways
Europe
in France many D-Day museums have aviation bits
Royal Military Museum - Brussels all Forces but a large old plane section
National Military Museum - old Soesterberg Air Base - Netherlands, all forces but pretty new
Kbely Aviation Museum - Prague lots older cold war ex Soviet planes and helicopters
Australia
Imperial War Museum Canberra
Most current RAAF bases have Museums in each state some on site some separate.
Have been to Pearce, Amberley, Pt Cook, Wagga, Adelaide, Townsville, Newcastle/Williamstown
Former WW2 bases such as Nhill, and Evans Head have started small museums as well.
Nowra Naval Museum has some planes
Temora Aviation Museum
Qantas at Longreach
HARS at Woolongong
Queensland Air Museum at Caloundra - large collection, lots outside
Small one at Caboolture as well if you are bored...
Oakey Army Aviation Museum
Woomera - Rockets