We had a Jayco pop up for 4 years and LOVED that thing. Hauled 3 adults and 4 kids

I think you need to ask yourself what you are going to do inside.

We were just looking for sleeping so a pop up was fine

If you are trying to have a house then you need a bigger one

A camper is something that most don't see as a good investment, money wise maybe so, for the family it could be a great investment, Time spend with the family and building family memories. I don't own a camper but my sister and her husband does and have for over 20 years. Their start out with a pop up for just the two of them and then move to a bumper puller (a family of 5 now) then just a few years ago went to a fifth wheel. That been said, what you are planning on using as a tow vehicle will play a key roll in what you will get (BIL went from a Ford F150 to a diesel F250 for the bumper puller). As for what to look for or which model, I will not be much help. But I will tell you this with a 5 months and 2.5 years old. Bunk beds are a great idea for several reason. 1. as the kids get older they will have their own bed to sleep in. 2. Look at bunk beds as separate bed room for the kids. 3. If you decide to take some buddies camping, your friends will like having a better place to sleep. 4. Young kids will go to bed before the adults and most camper with bunk beds setup can close it off from the rest of the camper. 5. With bunk beds you still have the dinette and/or pullout couch as extra sleeping area for other ( kids will want to bring along friends as they get older, plus if you have other family member you want to bring along.
Something else that have not been say get one with a tub (yes it only 3 feet) but with small children you wife will love it when it come to giving the kids bath. And last make sure that the master bedroom can be close off from the rest of the camper (you and the wife will really like that).
No one can decide if a camper is right for you and your family but you and your wife. You will have to decide if the investment is a good one for you and your family together time.