I can't tell you about the weather at that time of year because when we went, it was September. Here is what we did - Moki Dugway drive - awesome! Remember to stop at the top and look back. Natural Bridges National Monument - at the to of the Moki Dugway. Take the hikes to the bottom of at least one natural bridge. Goosenecks State Park - go back and stay there, for free, with your RV next time. Goulding's has a lodge and there's also some in Mexican Hat and Blanding. Here's a good link I found with information -
http://wikitravel.org/en/Monument_Valley