Looks like the Feds actually funded a 'loop' streetcar in Atlanta. I will be very interested to see how well it works out. 'Loops' are very attractive politically, because they provide a mechanism for more places to be adjacent to the line, but are operational failures. It's broadly acknowledged in transit planning that circulators don't work--downtown 'shuttle' services (rail or not) rarely have enough ridership to make them worth the cost, largely because its simply faster to walk than to wait (an infuriating situation). The 'river ratio' of straight line distance between endpoints vs. track length remains a very good determinant of transit line 'goodness' for a reason.
Working on Ogden Streetcar, I fought the idea of separating the streetcar lines into two uni-directional lines because I believe it makes riding the system more difficult. I recently rode Phoenix's LRT, which has directionally separated track--although only by 1/8 mile. I did not like it--I found it made using the system more confusing--I could not just walk back to my origin point to get back on the train, but had to find an entirely NEW location to do so.
The Atlanta streetcar is separated by 1/8 mile, but also includes a larger loop on the western end. It *may* be long enough to be worth riding (instead of walking). The 1/8 mile metric is significant because that's a SLC block--and if it works in Atlanta, it'll work here. IF it works in Atlanta.