We have stayed at Ruby's Inn twice for riding and have enjoyed the experience. The close in trails are more like forest service roads but there are some great trails too just takes time to get to them and find them.
In August we went to Marysvale, UT for an entire week of riding and camping and loved it so much we already booked the same site for the same week in August 2014.
Moab area would be 100 degrees in July/August. The Piaute Trail system or the area around Rubys would be higher and cooler. The warmest weather we had was 92 staying in Marysvale this August....
The key for fun ATV riding is finding the 50'' or 60'' trails....