I have a 3 or 4 LNB dish. But it's only one small dish on my roof. It also has an antenna that picks up all the local channels and merges them in seemlessy into the DirecTV box that connects to my TV. This way when I press 'Guide', I see all the cable channels and all the local channels on the same TV guide like setup. All the show/channel data is brought in as well. It's all digital as well, so the quality is very good.
We run 4 different TVs in the house. Each one needs their own set-top box, but all the video comes through the 1 sat dish.
Being a satellite, I wouldn't think location would make much difference, but what do I know?
edit: I just checked their website and it says that DirecTV brings local channels to 94% of US households. You could very well be in that 6%.