Just got back from 12 months travelling nth and sth america and here is my 2 cents on the Western US climbing areas:
Guidebooks: Join REI and buy the guidebooks then just return them two weeks later. I did this heaps it was great. Some areas I was only interested in small section of the guidebooks, so I just went to the library and photo copied the relevant pages of their guidbook.
Joshua Tree: We were there in May and it was way to hot to climb. So I think the only time you could go there would be October. Some good trad climbs but they are kinda spread out.
Indian Creek: Best climbing place we went. We were there in October and it was perfect weather.
City of Rocks: Awesome location, perfect weather (we were there in july) and not that crowded. Not a massive amount of pure trad climbs though. There is heaps of mixed and sports routes. Castle Rock is in the same area and is sport only and was great.
Little Cottonwood Canyon: Some great sports routes in a beautiful little spot just near SLC. But I think only a couple days worth at best.
Yosemite: Great climbing but found the hoards of people way too overbearing. But you still can't miss it.
Rifle Canyon: Didn't actually climb but did drive through and checked it out. Would be perfect for shade/sun depending on the weather as you can easily just switch sides of the canyon. Bullshit payment rules though: if you pull over your car even for a second you need a day pass which costs $10.
Boulder: Was balls in my opinion
Edorado Canyon: Near boulder therefore crap. Met some other aussies who went there and reckoned it was a chossy pile of fluff.
Lovers Leap: Was absolutely awesome in every respect. Great mid range trad routes and some hard sports climbs.
Have heaps of fun over there, sorry I couldn't suggest a heap of sports climbing options, but most sports climbing locations in the west are more of smaller areas with only a handful of climbs (Maple, Smiths, Rifle being the exceptions). Just speak to locals and they will direct to plenty of these.