The one that really bothers me is that you have to kill someone to take on the Dark Brotherhood. There should be a "good" way to trigger that questline. It wouldn't even have been a strain on the lore to have allowed it.
A good way to trigger get the DB to come looking for you? You always had to commit a murder in order to get the DB's attention... always! That's what the DB is about! LOL Plus, I really can't feel sorry for the old woman you have to kill initially! =p

That's how I did it. And yes, you can then still ask the bartender at the Ragged Flagon, though it will take more buttering up if you're not a member of the Thieves Guild.
...when I do the DB quests on another character, I'm going to kill the woman in the middle because she was the nastiest of the 3 when I let them go. 
