Top end:
Janos (and J-bar)
Anthony's in the Foothills (always named by Wine Spectator)- I ate here four times in the five months I lived in Tucson!
Hacendia Del Sol

Very nice but more affordable:
North (in La Encatada shopping center; also about four other restauraunts in the cul-de-sac but North is the best one)
Bistro Zin (I heard this may have closed)
Wildflower as described below- this and North/Bistro Zin have same ownership
Fleming's steakhouse (a chain, admittedly, but still good)

Cheaper but good:
Definitely second Casa Molina
Another Mexican place named Micah's I think, it's downtown and listed in fodor's I believe