Speaking as a gumby, the easy routes are a gumby scene on the weekends, but only on the popular rocks next to the road. Hike into the Inner-City, and you'll see fewer people.
If you get a guide book be sure NOT to get the Tony Calderone guide. I'm not sure if it's still in print, but for a few years it was the only one available (around '99 or so). I don't want to go into it, but that guy was a blight on the Salt Lake, City of Rocks climbing scene for years.