I don't think anyone answered the question I read in YodaMom's post:
Are there separate areas of designer homes?
The answer is yes, but they are all over TV. I live in a Designer-only neighborhood, but less than a block away is a Ranch-only neighborhood (the Ranch preceded the Cottage series). Not far from that area is a collection of Patio Villas.
It's unlikely that you'll see different categories on the same street, but most villages have everything from Patio Villas up to and including Designers. Premiers are usually all by themselves.
Hope that helps, YodaMom!
SWR