As the previous poster mentioned, TER is a good message board for general areas ... here's a link to their Atlanta message board:
http://www.theeroticreview.com/d ... List.asp?boardID=18
Unfortunately I'm not well versed in the east coast, but this should get you started.
The only problem with CityVibe is there's a lot of bait n switch and variance in service that you can't just book on pics alone. You definitely want to read some reviews first.
For San Diego, SoCal generally uses humaniplex. It's a bit more localized and there's a validity/ranking system, so it's less likely you have a bad experience.
http://www.humaniplex.com/classifieds/tags/?trid=11
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I guess the biggest thing I can recommend is that you read reviews of the girl first. It's not like HK where there's generally good service ... there's a lot of bad apples in the U.S. and doing your homework first helps. Worst comes to worse, just Google search a girls phone number and it will usually pull up the escort reviews if they've been reviews on any of the websites.
I know this might not be super helpful, but hopefully you can find some good options in your various travels.