The place mentioned by the two repliers above actually and officially is not part of Davis-Monthan AFB; it´s an annex called AMARC, but still military.
for further info.
Tours of AMARC are organized and carried out by PASM (Pima Air and Space Museum, Tucson, AZ
However, be advised that that tour will NOT let you get off the coach when visiting AMARC !
PASM itself has a wide selection of military a/c stored outside with some of them being quite weather beaten.
Located between PASM and AMARC are a number of private scrappers who get those hulls that are discarded off by AMARC (but there is no guarantee what to see at any given time).
So if its not a Museum with high-polish exhibitions that you want to go to, a visit to sunny Tucson might be a thing to consider ...
Located south of Tucson is the very interesting Titan Missle Museum (see link on PASM website).
Some more civilian a/c storages are also located near Tucson ...
Carpe diem ! Life is too short to waste your time ! Keep in mind, that today is the first day of the rest of your life !