Flagstaff would be my choice, but fewer folks know about it. I think a year ago or so, Triathlete magazine ranked it the #1 place to train. Might be a little bit of a stretch, but you could do worse. It is by far, a smaller community than SLC or Bay area. Flagstaff is about 75,000. Depends if you like that or not. Perhaps not ideal for cycling Nov.-April, but neither is SLC. Open water swimming is limited to Upper Lake Mary (20 minutes East of town), and it’s seasonal too (May-Oct.). However, you are at 7000’ and up, you’ll get a huge altitude boost from training there, tons of runners and cyclists, swim programs for Masters at NAU, and a really nice friendly community. Palo Alto is great, but very congested, same for SLC. If you need a lot of infrastructure around you for training and such, SLC or Palo Alto might be better. Big athletic scene in “Flag”, especially runners and “altitude training” visitors. Good Tri scene to the south in Phoenix and to the West in Las Vegas environs (2 and 4 hours away respectively). Summer multi sports events in Northern Arizona include Mountain Man and Deuces Wild Tri festival, both great events. Lake Havasu City has a good fall and spring racing scene. Flagstaff would be pretty close to ideal if your focus were Xterra, off road options Spring though Fall are incredible. I did a lot of road riding there prepping for IM Coz last fall and thought it was perfect. Had 3 or 4 great long ride options with very little traffic. Pay a visit to each of these communities and feel them out.