100%'ing them, I just don't have the time or will to do so anymore.
Talk to many of the NPC's wandering around town... most of the time. There are some games where I will.
Replay longer games, unless there is a very good NG+ feature or additional NG+ content.
Online multiplayer. I only do this with my kids and partner these days (as a group). My kids like public multiplayer, but I find other players are oftentimes just idiots.
I also kinda agree with the running through the world without appreciating them. But, I've always appreciated environments a certain amount. I'm an artist / CG artist so I guess I would.