I have not been in the Phoenix/Scottsdale area in years but there are a whole shyte load of trails with in riding distance. A fun place to ride that a lot of my buddies go to is South Mountain. As the name implies, it is on the South side of Phoenix. Any shop around there should be able to tell you where the good trails are.
What I did when I lived there was step out my door, decide which hills/mountains looked good and headed of to them. Most of the trails are not too difficult but if you are there in mid summer you will have to get used to riding in the 120 degree heat. It is not as bad as it sounds but you should carry two H2O bottles and a 100oz hydration pack. Possible get some light shin guards for those untimely scraps with the cacti and rocks 
DBD
Last edited by dirtbikedude; 10-23-05 at 04:47 PM.