I thought about the iMac too. Won't have the keyboard issue. It's an option but I ended up going for the latest MacBook Pro. I like being portable. Bought the extra warranty and I hope I don't have a bad experience.
As you'll see from my signature I have the iMac/Macbook combo. I already had the Macbook at the time of my iMac purchase and so that changed things a little, but in hindsight, I would have done things differently.
As much as I really love my iMac it would have been much more practical to just have one computer with everything on it. Right now I do the dropbox sync dance. Personally, I'd say just get the best portable you can afford that fills your needs and add an external monitor like most do.