I think we need more than just 4 or 5 zones in the US. For instance, for the pacific timezone, there could be ones in Portland and San Francisco. I think the regions should be planned around the concentration of persons that live nearby. For instance, if there is nobody in Alaska, we shouldn't have a location near to there, but SanFran has a high concentration of TS and it makes sense to have one there, but I'm not driving over 600 miles to get there.
Melissa