While I do agree there is a lot more to see and do in downtown area(touristy stuff, better restaurants and bars) you can get to Alpharetta via public transportation and stay up there if you want and not have to rent a car.

Take Marta train to end of line North Springs, then get bus 140 to Mansell Rd/North Pt Pkwy(or 185 during the week). North Point parkway is a mall/strip mall road with plenty of hotels, restaurants, and shopping(and is safe to be out at night in my opinion). You can stay there and walk to Encore Park if reasonable fit. Encore Pkwy dead ends into North Pt Pkwy. Look at google maps of area.



This would save you the rental car money and parking in downtown.

Things to do in Alpharetta(I lived there for about 10 years pre Encore park): Big Creek Greenway- for running, Atlantic Seafood Company-Whitney and Bobby's former favorite, The Varsity on Haynes Bridge - not the full Atlanta experience but still good and its a "Frosted Orange", Sage Woodfire Tavern on Haynes Bridge - if you're into Cougars