I have two of these:
Outward Hound Car Booster Seat - Travel - PetSmart
They work really well and match the leather in my car. They fold down really easily to make way for groceries, people, etc.
I saw the lookout seat that you mentioned and would like it if I had more seating (in a SUV) so I wouldn't have to remove it. It does look SUPER comfy and stylish! I also wish that they were cheaper... along with every else in our society right now!