Rating: +1
In my opinion, no, there is no "harm" to be done by adding "Atlanta GA" to your title tag. However, some people may disagree, because any word that you add to the title tag will decrease the keyword density percentage of your most desirable phrase.
For example if you want to be found by "affordable blue widgets", but your title tag is "affordable blue widgets - Atlanta GA" then you have lowered that "keyword density" for your most desirable phrase.
Frankly though, (again my opinion) Google has placed even less relevance on the title tag lately, and is focused far more strongly on the anchor text and authority of your inbound links.
So if you get enough people to link with you with the phrase "affordable blue widgets" then you're still going to reap the full benefit of ranking for that primary phrase, plus you'll have the added bonus of ranking even better for "affordable blue widgets in Atlanta".
