I don't think we should segregate people by religion...in fact, I don't even like the idea of one religion dominating in an area.
I live in Utah right now, and you always hear people complaining..."I can't wait to get out of here and move somewhere else!" I have this attitude also, and it isn't because I hate Mormons (I am one after all!)...
I believe that diversity of religion actually helps people to practice their own. For me, it was much easier to tell a friend who was not of my faith that I didn't do something than it was to tell someone of my own faith. It takes away the, "I can't, I'm Mormon..." excuse and the peer pressure can be a lot stronger.
When you are put in a position of representing your religion around people who are not of the same faith, I believe you set higher standards in your own life. Defending your faith and answering/pondering the "tough" questions helps your faith grow and helps you learn. This may be a reason that many people come to this board.
I experienced the minority side as a Mormon living in Germany. The area I lived in was overwhelmingly Luthern (Evagelical) and I hated being a minority. I really felt like people treated me differently. I was told at a bank that I couldn't open a savings account because they "didn't want to be affiliated with our organization." I talked with friends who actually lost jobs and were kicked out of their apartment because they did not conform to the dominate religion.
I loved growing up in Washington, one of the most religiously diverse areas I know of. You could live your faith, and nobody really cared. In fact, people actually respected people of faith, even if they did not agree with it. People are afraid of things they don't understand, and you will never understand something you are not confronted with.