The Ho-Chung Gaming in Madison, WI allows overnight RV parking. They have a special, designated parking area for RV's.
This is a nice casino with plenty of gaming and dining options. They do allow overniht RV parking.
The Gray Wolf Peak Casino in Missoula, Montana recently opened. This new casino currently has slots only, but the does allow overnight RV Parking with free electrical hook-ups.
Creek Entertainment is a RV Friendly casino located in Gretna, FL. In addition to slots and table games, they are also a race book. They do allow overnight RV parking.
Information on the Desert Rose Casino in Alturas, CA added to the site. This small casino allows overnight parking for up to three nights. Very quiet location.