America West is a decent airline considering it is a national carrier. I travel through Las Vegas and Phoenix quite often through America West and so far, I have not had any real problem with them. However, many airlines are adopting the "cattle class" seating arrangement (more seats per plane = higher revenues for airline = decrease in legroom and comfort) such as British Airways has on some of their 777s to tourist destinations (e.g. Miami, I think). America West is one of these airlines that is adding more seats per plane and I noticed this on my flight from San Diego to Phoenix during the summer... The seat in front of me was barely touching my knees and there was hardly enough room in the overhead bins to fit the bags of all the passengers... So, hopefully, you will not be aboard one of these cattle class aircrafts. As for Phoenix's SkyHarbour airport, it is very well laid out, especially Terminal 4 (which America West uses). Again, the big problem with Phoenix's airport is that it doesn't have enough runways for the number of airlines that fly there, which causes tremendous delays and schedule changes (be cautious of these!). According to Travel and Leisure Magazine, America West had one of the highest number of delays for national carriers, although, this has been blamed on the Phoenix airport traffic and not on the airline. All in all, I think despite the "little" problems, America West is definitely a good airline (way better than US Airways, for instance).
Have a good trip!