I've spent many, many hours on Oblivion, and I don't doubt there will be many more. I have GotY edition for PS3, so no mods for me (I just bought Morrowind for PC, though, so I can download some mods there).

I've finished the main quest, gotten to the top of all the major guilds and have done about 120 quests (all of this in two files, though, so it's a bit difficult to get an exact number of the quests I've done).

I've also bought three houses and have bought just about one horse from every stable (they keep dying on me), and am at level 30-something with my main save. I have no ambition about doing absolutely everything in the game, but I will keep playing and see how far I can go.