I lived in Phoenix for a few years but I don't know the level of kayak activity/stores/rentals that might be available. There is more boating activity than those just passing through might realize however. There are a number of great lakes up in the Superstition Mountains that many boat on. There are marinas up there that might even rent kayaks for all I know.

But I agree with erez that this is a great time of year for hiking in the Superstition Mountains. One such hike is to the Fremont Saddle overlooking Weavers Needle. This is a very popular hike so I suspect most hotels could tell you how to get to it. 4 miles - 1400 ft elevation gain. Earl