I was in the same boat, but I've since sworn off shoulder bags. They simply get to be too much for the migraine sensitive neck muscles and always seem to swing around at the wrong time. For events and travel sightseeing, I use ThinkTank holsters. The weight around the waist is a lot easier to handle and I can slide them around the belt to gain access or get them out of the way. For many events, I always seem to use the same camera most of the time. The holster approach gives me the option leaving the almost always empty holster at home (or in the car).
Specifically, I use a ThinkTank Digital Holster 30 v2.0 for my 7D and 70-200 f2.8L II with hood in shooting position. No more need for the lens cap. For my 60D and 17-55 f2.8 with hood in shooting position, I use the Digital Holster 20 v2.0. This bag can also handle a longer lens. I use these bags on ThinkTank's Pro Speed Belt. One word of warning, these belts run a little big and seem to stretch a bit during the first few events. On rare events when I want a flash or a small prime, I add a small utility bag to the belt.
This is a very flexible solution and the lowest profile that I could find. Of course, they do scream "camera inside". Some food for thought if you're open to alternative solutions.