Moab has lots of special interest group gatherings that have gotten crazy big like the Jeep, utv, atv and bicycle events. I would check with the local visitor information center for dates before chancing the crowds. You could always go a little farther to HWY 95 and venture off. We hit Lake Powell 13 years ago and still have not seen all there is to see. With a National Parks Pass you can boondock on BLM land and get showers and dumpster while spending the day on the beach, drive a few miles and sleep on BLM land for free. Give me a PM if you have questions and do bring plenty of long storing food! Spring and fall are best as 100 degree days a common in summer. Henry Mountains are 20 miles away and at 11,000 feet cooler in summer sometimes still snow patches till July.