The area is top notch. My condo building is across the street

Plus the lobby is always busy so they  aren't  to nosey

Twelve is nice if you get the larger room -- it feels like a nice little apartment -- you have a separate den, bedroom, and a nice large bathroom (with a separate dedicated shower and bath rub) -- its great for an extended stay

Twelve Atlantic Station is a little nicer in terms of area because you have Atlantic station at your finger tips (restaurants, shopping, even a grocery store steps away) -- plus if very safe during the day as there are lots of people roaming

If you want "very nice" go with Loews, Mandarin (a little stuffy atmosphere and if your girl is not 'polished' she will somewhat stick out amongst the clientele there), Westin Buckhead, or Intercontinental Buckhead -- you could also get a W higher end room if you're splurging for ultimate debauchery ambiance