Modified olympic is my vote. A course featuring beat reach reach beat run beat makes it a well balanced race course IMHO.
I've raced enough monodulls in my short life to know first hand how annoyed skippers of particular boats get when the RC runs nothing but windward lewards. Modified olympic makes it a race for both the reachers and the runners
Cats being a reaching kind of boat, why not throw in an afterburner igniting leg or two?