The local criterium circuit event continues in Sandy Springs Sunday, May 5th. The Sandy Springs course has more hills to it which can offer different perspectives. Races start at 10am and run through 7pm (end of Taste of Sandy Springs).
Here's a link to the 2012 map. BTW, the map is a very large pdf file, 38mb so it may take some time to download. The web site hasn't listed a 2013 map so I'm guessing no changes will be taking place. Parking areas are listed on the map. I don't see the need to have a designated location to meet. Feel free to come and join the fun any time during the day.
I would suggest parking in the Whole Foods Market parking lot at 5930 Roswell Rd. This should allow for easy in and easy out through out the day.