Relatively native Atlantan here. And by Atlantan, I mean Atlanta proper and not the burbs which is where 99% of people who say they're from Atlanta actually live.
Anyway, I'm super familiar with this area. If you're just going to the Fox Theatre for a wedding or a show or you have a car, Hotel Indigo Midtown would be fine. I would highly recommend moving to a hotel a few blocks further north than that though if your goal is to try and use public transportation and explore the city. Anything south of North Ave is legitimately sketchy, and you will not want to walk around that area. Aim for staying closer to the Midtown or Arts Center stations--preferably closer to 10th St. If you can walk to Piedmont Park, even better. Way nicer area for walking around, far more restaurants, and in general, there will just be more pedestrians around.
And while I appreciate your desire to use public transportation, Marta legitimately is not good. It's great for getting to and from the airport. Trains are fine--there may be the usual weirdo, but it's basically safe. The buses are just too infrequent to be reasonably used unless you get lucky with timing. I live on two bus lines, and I think that's the exact same number of times that I've used the buses. They're scheduled every 40 to 50 minutes making them totally impractical. If you have all the time in the world to make a ten minute trip by car take one hour, then go for it. But expect to take an Uber or Lyft or two.
