I am some what of a regional expert (i live 1 mile from Indian truck trail) N Main Divide starts off the 74 just above the Hells kitchen. You can take N Main Divide all the way to Santiago peak (i have only taking Indian truck trail, which dumps into N main divide). On a clear day you are supposed to be able to see Catalina from the peak.
S Main divide however leads all over mainly ending in Murrieta, haven't explored that area yet though.