New Setup

Hey PJW, welcome to AC. I can't give you specific region advice, but I will tell you that because a fish is listed as prefering "x" ph, or "x" temp, doesn't mean they absolutely have to be in that range. Some fish are more sensitive to certain parameters, but in general, fish can tolerate ranges outside what is listed as preferable. Also, a steady ph is better than a fluctuating one. Just in case you were going to alter your ph to achieve that "desired" range.
You could pick any region and get a fair number of fish that would like your water. I would suggest researching each region and more importantly, the fish you would like from each region to see if one or more of those desired fish is a sensitive species. That may help you decide which one to go with.
Of course, with SO MANY knowledgeable people at Aquaria Central, you just may get the answer right here!! Good luck

Try running a search on Biotopes. Seeing some pics may help. Here's a link to a site that is pretty useful...

http://www.mongabay.com/fish/biotope.htm

Check out the fish listed, and see what appeals to you. While I agree the biotopes are really cool, sometimes the fish you most want will be hard to build around, so don't feel obligated to restrict yourself. Also realize that some fish are predators--they won't fit into a community environment well, especially mixed with their native food types. Sometimes a close substitute that's a bit bigger will be a better choice.

http://www.biotopeaquariums.co.uk/index.html

try here. its a pretty good site, but the mongabay is very good also.

hth