A loop of the City Creek Trails incorporating the Over the Top trail would be about 10 miles long and involve 1800 feet of altitude gain and loss...
From the South Grand Avenue car park head up City Creek Trail to Bench Trail then Burrito, Lichen and Serengeti. That will take you to Cusick Creek where you follow a steep old eroded 4wd track to Over the Top itself. Phew!
The gradient of Over the Top is generally well controlled but you'll need to be fit and strong to avoid a bit of pushing. Once at the top the views go on forever. There are some rocky sections on the way down, some side exposure and lots of tight switchbacks. Apart from that, it is not technically rich.
At lower levels you'll meet many forks and there are several options to get back to the car park - just keep your front wheel pointing roughly down. One good option is to go left into Sullivans, then take Cross-cut into 911 and the Bench Trail back down to the car park.