Thank you all for the replies! Someone recently told me that "most rv'ers" think it's safer not to wear seatbelts unless you're in the cab. I thought that sounded a little nutty but I don't know many folks who've owned motorhomes so I thought I'd ask here. I got the answers I pretty much expected.
My kids are 15 and 18 and I will be making sure they're buckled up when the vehicle is moving. I've never worn a seat belt in my life in any vehicle but I've been trying to change my ways... Maybe this would be a good time to start ;)