So, a BLT studio is about the same size as a room at POR, but because the BLT studio has a kitchenette taking up space, the way the space is used is less efficient. When the sofa bed is out, you will absolutely feel it.
For a family of 3, I prefer Poly, because you can use the queen bed and the murphy bed and never touch the sofa to pull it out, just to sit on or stack laundry on.
Renting, you should be able to get BLT Lake View or Poly Standard. I would never count on BLT Standard, as that category is quite small and popular. Poly Standard is a huge category - 300+ units.