We had a Jayco Jay Flight 26BH as our first camper. It was pretty much perfect for a family with 2 kids. It was a pretty standard design with no slide. That made it a good first camper for us. Standard dinette, not u-shaped, which worked well. No outside kitchen which means more room for storing things and more room for the bunks.
As the kids got older and we added a dog, it started to feel a bit small. Hard to work in the kitchen and have someone pass through to the bunks or bathroom. Not enough room for us all to watch TV comfortably. Top bunk was a single which we heard some complaints about as the kids got above 15.
If you want a bit more room, there are some units with a slide. Consider getting a super slide with couch and dinette in the slide. Consider ensuring there are three beds (3 bunks or 2 bunks + sofa) so each child has their own space. There are a few triple bunk campers available in the size you mentioned.
To get started, take a look at a Jay Flight 26BH and Jay Feather 27BHB.
When shopping around last time, we ended up getting a Grand Design Transcend. So far, it seems like a good quality unit. For what you are describing, maybe the Xplor 247BH, 261BH or 265BH.
Note that there are other good travel trailer manufacturers and models. I'm just sharing our experience.
