You can view all of the places to stay within Nauvoo at Welcome to Beautiful Nauvoo, Illinois and while the humidity can be stifling at times, it is hardly ever 100 f in September at 10 pm. The website above also has a list of all of the events going on in Nauvoo - there are plenty of things to see and do at any time of the year. A car rental would be very helpful as Carthage is approximately 30 minutes from Nauvoo. Quincy is 45 - 60 minutes (depending on where you are going in Quincy) and also has lovely sites to see. Hope this is helpful!
