I make no claims that any of these are "the best" in the nation (which is a retarded notion, anyway)...but these are joints I've enjoyed, and if you're visiting any of these places, they're worth checking out:
* Austin - I have three I frequent
**Mangia - Chicago pie-style -
http://www.mangiapizza.com/
**Salvation - Cracker-thin crust -
http://salvationpizza.com/
**Southside Flying Pizza - Outstanding red sauce & oven-fired -
http://www.southsideflyingpizza.com/
* Stillwater, OK - Hideaway Pizza (it's different/better than the ones in Tulsa and OKC) -
http://www.hideawaypizza.net/
* Salida, CO - Amica's Pizza & Brewery -
http://www.amicassalida.com/
* Chicago - the previously mentioned Giordano's