Before I went digital, I had two F-1 cameras, and the lens I most often used was a FD100 mm f 2.8. I think I used it in about 60 pct of my pictures. 100mm is ideal for portraits, and is also fine in the theatre (I had Ektachrome pushed to 800 ISO which went well).
You will also be able to take some outstanding landscapes and snapshots with it. In other words, a fine all-purpose lens. In my opinion it will give you much more pleasing results than wide-angles.
If you wish you may supplement it with a 28 mm or something similar. But you may well find yourself using the 100mm much more often.
Today, Canon has a EF100 mm lens at F2.0 for around US$506. You will probably be able to use it indoors without flash (much to be preferred!) as today's cameras will allow you to shoot at 1600 or 3200 ISO (or even at 25600 ISO if you are the happy owner of an EOS 5D mkIII). The rather shallow depth of field is ideal for portraits.