I like RPing. Not that I don't do so while in actual quests too.
Right now I have a Thieves Guild leader character and in my head I have this RP going that she gathers agents all over Skyrim to work for her. 2 to 3 of them live in each house I own (All of them except for Dawnstar's, Morthal's, and Windhelm's) and I can spend hours basically just going to each one to check up on these Agents. Sometimes it involves carrying books or weapons to fill the shelves and racks, because the Agents need to be entertained when they aren't working and prepared for attack. I haven't got so detailed as to give each Agent their own particular job, but Derkeethus and Lydia were the first, so they're like second-in-command.