I'm curious as to which ones you think those are. And I'm posting (rather than sending a private note) because I think the question has some general interest. My wife and I, once urban pioneer types, now live over 30 miles from Atlanta, but we drive downtown at least four times a week for services or ministries at Our Lady of Lourdes church. Our parish now has four weekend masses, and three of them are always filled to capacity. Midnight mass at Christmas was celebrated in the gigantic new sanctuary at Ebenezer Baptist Church, and our Easter Sunday masses will be held in a concert hall because we just do not have enough room for all the people who want to attend.
Many of our fellow parishioners also travel long distances to come to Lourdes. So in the case of our own parish, it seems to me that physical proximity to the church buildings is not all that important. I suspect that would be the case elsewhere if more parishes offered a beautiful, reverent liturgy and a variety of opportunities to serve in meaningful parish ministries.
I was really thinking of the predicament that Immaculate Conception finds itself in, not a soul living within a mile of the place (I think there is one new downtown loft a couple of blocks away, but other than that and Georgia State University, nothing.) It could find a niche as an historical church, but it's a little anomalous -- they've moved the altar out from the gorgeous old reredos, and it's a very "contemporary" parish - which doesn't exactly lend itself to historic preservation. I only attend on weekdays, but if there are ten people in the entire church it's unusual. I understand from talking to people at the church that the services on Sunday are pretty small also (relatively speaking).
I think Sacred Heart is the other truly "downtown" church, i.e. in the business district and located fairly far away from a residential area (although there are some new condos fairly close by). Acc to their website, they concentrate on homeless ministry and serving the hotel/convention trade. . . they're right at the end of "hotel row" on Peachtree.
I have no idea how many members there are at either parish or what their average Sunday attendance is - but IC is fairly desolate on weekdays.