I had the 50/1.8 (with my 400D) and it was a good start, but I couldn't arrange with the focal length.
It was too close for me indoors, and even outdoors it was either too close or not close enough! That's the reason I bought a 28mm and right after that the 100mm, so I walk around with one of them :-). The 28mm gives me a nice to use 44mm full frame equivalent.
I'll probably will get a 50mm when I am going full frame, but as said the 80mm full frame equivalent didn't suit me, and now I am wondering for what you are using the 7D + 50mm indoors? :-)
50mm can be use on crop bodies as a portrait lens. 85mm can be used for head shots. The 50 and 85 on a crop would be similar to the 85 and 135 on a full frame. It takes some getting used to if you're used to shooting wider focal lengths, but the change in perspective can be refreshing.
Yeah, but a 50mm on a crop has a view of an 85, but the perspective of a 50, and for tight portraits that's not the best combo. The 85 or 135 (even your 200L) on a FF would be much better.