As previously mentioned, there are a few places that will not allow the pop ups. In addition to Fishing Bridge at Yellowstone, I know that some of the national forest campgounds along the Wind river coridor are also restricted due to griz.
The real consideration for me in moving from a pop up to a hard side is that even though pop ups are allowed almost universally, you still have all the restrictions of tent camping in bear country, namely, having to store all food and smellables outside of the camper in bear boxes. To me this is a pain and I hate to spend 20 minutes in the morning hunting down my coffee and what not. Much better to have the pot on the stove and ready to go.
I would recomend thinking about a vintage airstream. As a point of reference, my 1968
Trade Wind is 24ft, has everything (shower ect), weighs about 4K empty and is verry much towable with a half ton. Furthermore, with a little careful shoping they can get into a nice unit for about the cost of a new pop up. The airstream should hold its value and outlast a pop up. Just my thoughts for what it is worth.