Here's what we've done in the past, and why we've made different requests depending on who is going with us.
With another family...
We usually need the extra bed, and I would rather have two beds than a bed and a pull out sofa.
When just the 4 of us...
It bothers me that the kids are in a room with a door. When you have a dedicated 2-BR, the only entrance into the unit is the main door (which enters into your kitchen/living area). Plus, both kids have a queen bed and not a pull out.
If grandparents are coming...
My parents sleep in a queen bed together. So, the studio would be like a mini-apartment with its small frig, sitting area, and extra door. It allows them to come and go as they please without having to come through the main unit.