Don't worry about the RROD, that was fixed while they were still making the old phat ones. It's just the really old ones that did that. Shouldn't be an issue with a new one.
The 250GB HDD is really a must have. You should decide on if the Kinect is going to be a nice toy for you and yours, or if it's a useless gimmick. Some people will love it, and others won't dig it at all. I still haven't got one personally. But they are quite expensive to buy as a stand alone, I think they are cheaper in bundles. As far as I can tell, they make the user interface nicer, and they are nice for social/party games and for kids. And there's kinect voice command support for Skyrim, which looks interesting.