B.,
If I were you, I'd attempt Supernanny again. It might be too late, since you've given in and stayed in there with her, but maybe she'll be more receptive since she's more used to the bed. Another thing we do is let my son take some books to bed with him. He lays in bed and reads them before he falls asleep, then we take them out when we go in to check on him later. The rule is that he can have books in bed, but no toys, and he has to stay in bed.
She's 2, so she's ready for this, and most likely capable of understanding that this is what bedtime means now. You have to be firm and more stubborn than she is!! I would say absolutely don't comfort her when you go in, or she'll keep crying for that. When you do the Supernanny, you have to go in, put her in bed, and walk away. No talking, no comforting, no attention, except maybe the occasional, "It's time to go night night." If she keeps following you out over and over and over, say, "Night night honey," walk out, and close the door. Let her cry. Go in every 10 minutes to put her back in bed. Don't comfort or speak. If she can open the door, put up a gate, and again, don't visit or allow her to see you but every 10 minutes. If you are as stubborn as she is and are completely consistent with this (it may take several weeks - be ready for that) she will realize that you're not giving in and she's gotta go to bed. Be firm!
Best of luck,
Amy K