Okay, so here's how the roundabouts work in Australia. This is a three-way at a normally very busy intersection in the surfing resort of Torquay, Victoria, AU. I've used it several times. It works.
Color code:
Red: Vehicles must (EDIT) yield to vehicles already in the circle. Pedestrians can't cross here.
Green: Vehicles do not give the right of way to pedestrians in order to keep the traffic flowing.
Magenta: Vehicles should give the right of way to pedestrians, but are not required to.
Blue: Pedestrian crosswalks. Pedestrians can't cross the green areas if a vehicle is coming because that would stop the flow of traffic. Pedestrians can cross the magenta if a vehicle stops for them (which the vehicle should do).
This way the traffic keeps flowing. If you're gonna mix up a roundabout (which again is designed to keep traffic flowing) with pedestrian crosswalks, this is the only way to do it. It works in Australia. I've been at this intersection quite a few times.
Note: They drive on the left side of the road in AU, so things would have to be reversed in the US. Except in one place I know of -- on the bridge at I-285 and Ashford-Dunwoody road, vehicles drive on the left.