Good purchase. We own two of these badboys and they got us on the water and got us hooked so we had to buy a 14 foot raft after about 3 seasons with duckies.
That being said, you need some good quality experience before jumping in to whitewater. There are numerous lakes in and arounf PHX that may be a great place for you to get the rig wet and see how it handles before putting on a river. Go up North and check out Lake Pleasant which is beautiful and often not that crowded. Multiple nesting pairs of balds also.
The salt that you refer to is a technical and serious wilderness run that is probably one you will want to wait a season or so before trying.
Though it is clearly a party float and filled with college folks, the lower salt just out of town could be a nice intro to moving water in your new ducky...no real rapids, but a nice float to get aquanted with rivers.
Next, I would travel up north a little further and run the verde...call the shops in and around Sedona, search on here and get Paddling Arizona guide book...the verde offers class II and III runs to build up to.
Further north in Utah, there is the San Juan which is permitted, but you could easily get a date to do your first over nighter if you are flexible with the time frame.
After you have built up through these, the Moab daily is a great float within a day's drive and offers fun and splashy rapids...possibly this could be a great goal for you by the end of the summer or so.
the Animas Daily is a fun and splashy run, and at low water will be ideal for you...a good July/August trip up there would be great for you. Above that in Pagosa Springs there are short flatwater runs that are scenic and would be great practice
The point is...work your way up, and get familiar with youir gear, your skills and introduce the boy to the water life. You have made a smart purchase, enjoy.