Questions About Pet door / Cat door & Scratching Posts

We just acquired 2 cats, and have put their litter box in a basement bathroom. We want to put cat doors in several interior doors so we don't have to worry about someone inadvertently closing a door and separating the cats from their litter boxes.

My question: Do any of you have an opinion about the best brands -- best made and thought out? We don't need to worry about security issues, since these are all internal, but I don't want them to look hideous or to fall apart.

Also -- do you have any thoughts on best source for scratching posts and/or perches? They all seem so expensive and at the same time shoddily made. . . ..

Thanks!