I have lived in both Tucson and Phoenix... both have their pluses and minuses. I currently live in Phoenix.
What are the reasons you LOVE living in either Phoenix or Tuscon? I love living in the heart of Phoenix - I am close to lots of culture, public transit (which is, for the most part, sorely lacking in AZ), and other fun things to do. There are lots of parks and kids stuff around too.
I really loved Tucson for the same reasons, though Tucson is much more laid back than Phoenix, much more arty, much more crunchy. It is also much harder to find a job... hence my current residence in Phx. I would move back to Tucson if I could though.
What are the "crunchiest" neighborhoods of each city? Tucson is crunchy as a whole, but if I were to move back, I would live in the University area of town - in one of those old cottage style houses. Neat.
Phoenix... I can't think of a specific "crunchy" area. There are lots of families in the suburbs, that may count. Maybe Tempe counts?
Approx how much can we expect to pay for a 2 bedroom rental in a complex with a pool?
This varies a lot... We live in a 2 bedroom rental in a complex with a pool in downtown Phx, and we pay $750/month. Our last place had the same specs, but cost $1350/month. I couldn't tell you about Tucson's rental rates, except that they tend to be a little cheaper. I paid $500 something for my last apartment there, I think.
Any student nurses or graduates of nursing programs that can comment on good RN programs to look into? UA in Tucson, ASU in Phx - these are tough to get in to. ASU is one of the best in the country, I hear. The community colleges also have good RN programs, to which you are guaranteed admittance (eventually). I think Phoenix College has a program, though I know nothing about it.
Are there good food co-ops and farmer's markets? Definitely. There are tons of options in this regard, in both Phx and Tucson.
Is finding employment very difficult if you are not a FLUENT spanish speaker? Not a problem at all.
Good luck! Let me know if you have any followup questions.