I've only rented RDR, but seriously? I spent most of my time just goofing off, looking for treasure, breaking horses, or doing random road side quests.
I agree, I hardly did the main quest most of the time. I spent most of my time totally goofing off and doing what you said, plus exploring and tons of gambling and hunting.
I hope L.A. Noire does the same thing, I want to be able to almost ignore the main quest most of the time and do side missions, go to Jazz clubs and listen to some swing, drive around and see everything in LA, go watch some Hollywood movies in some of the theaters seen in the trailers, go to restaurants and bars, buy new suits, etc.
That stuff plus the detective work would for sure be on my favorite games of all time list :hubbahubba: