I'm not currently a Class C owner but we did research them pretty well when we bought the Winnie. We have had two rigs and while the Winnie is great and we bought it with the DGKs in mind they are at a time where while they want to travel with us, they are too busy with becoming adults and doing a pretty good job at it I might add.
So for several reasons we find ourselves with a rig we could easily full time in, it is just too much to deal with now.
We did carry a inexpensive dome ten at time and the kids did sleep in it under certain circumstances, like an extra friend coming along.
We expect that in two years the grandson will be almost 19 years old, he will be studying a lot and dating more and more. College is diffidently in his future so he will probably living close to us for awhile. He is also soon to become an Eagle Scout and camps a lot with his troop and their combined special troops(Philmont, National Jamboree). He may on rare occasions go with us but I think more with friends.
The DGD is engaged and will be moving to Oregon in a little over a year. She and her huband will both be going to school and working so we don't expect to be camping with them very often. She has 12 more years of college, veterinary school and internship.
So that leaves us with a rig that is really too big for the two of us. We knew that going in and have been looking at smaller since we bought the Winnie two and a half years ago.
I would plan on buying a 30 foot or so size rig now with the full expectation of buying another rig when the kids are out of the house. We well know the value of camping with your kids and with the grandkids and hopefully for you, the grand kids will like going with you and the larger rig will see a lot more family use before you buy a "just for two" rig.
Keep us informed on what you buy and how the family adapts to motorization. Don't be too concerned about the seat belt thing, the couch in a 31 footer will have them as well as the dinette and headrests are really an non issue. Maintenance is very important because these thing are expensive to repair, however, if your husband is handy, all the appliances(except the genny) are the same as in your S&B.
Good luck and straight and gentle roads.