I've seen some showrooms in the Miami Design District also, which is just north of 195 by US-1.
In Coral Gables there is a place also.
Like Phil said, in South Florida there are lots of showrooms and companies, but not many places where you can just browse. A lot of places work off of contractors calling them and then they design a whole house (Crestron, speakers, lighting, security, so forth), but the operate out of warehouses. Everything is so decentralized down here it doesn't make much sense to maintain a retail showroom.