I swear by Craigslist. I've sold two of them via CL and neither took a long time. I had an older class C that I was able to sell in the winter time in Vermont ... and made money on it. We sold our class A on CL also.
All that said it is more about how you advertise versus where. Craigslist has my favorite price. FREE. They also permit 24 pictures and as far as i can figure there is no amount of data you can input. No matter where you decide to advertise make sure you include as much information as possible. Remember that some people that are searching are new to RV'ing. Describe in detail all the things that you would look for in your next motor home. Give the mileage. Give the model number. Advertising it as a Fleetwood Bounder leaves out a lot of info. Give the year and state that it is a 34J. Obviously that is just an example but it baffles me how some try to sell their motor homes. Give the age of your tires. That info is readily available and it is a question I have always asked.
Make sure that when you take photos that it is free of junk. Can't tell you how many I've seen with boxes, blankets, folding chairs and just plain junk all over the place in the photo. Very uninviting and it screams (to me at least) that you don't really care that much about what you are selling.
Pricing it is tough. They are generally worth a lot more to the current owner than they are to the prospective buyer. Do your research and find out the value and price it accordingly. Make the listed price attractive but leave room to negotiate. Everyone wants a deal. If you can meet at an acceptable dollar amount, then you are both happy.
The short of it for me is Craigslist, photos, description and a fair price.
If you have friends who make you laugh, spend lots of time with them.
2008 Winnebago Sightseer 30B