We've got that one, and I really like it! My girls are about 12 and 9 or 10 lbs, so they are both bigger. I keep a blanket in there for easy clean up from muddy paws, etc, but the cover is washable. I honestly haven't used the drawer for a single thing, but it is nice to know it's there.
I don't feel like the attached pictures have a very good perspective, but they do have plenty of room in there, so they can have personal space if they want to.
There should be a few more pictures of them in the car seat in this album too:
http://www.facebook.com/pages/Doggie...27980630575982