For portraits, the Canon 85 f/1.8 is the way to go. You may also wish to consider the new Sigma 85 f/1.4 which has received stellar reviews and is very reasonably priced (compared to the Canon 85 f/1.2).
+1 on this. I bought both Sigma 50mm and 85mm oversea recently but i trade off the 50mm for a EF 28mm f1.8 as i find that the 50mm to have some focusing issue on my 5DMKII. Sigma 85mm really is a gem, it produced nice color and bokeh.