Depends if you like to change lenses or not, and what you're trying to photograph.
If you think you'll likely be too lazy to change lenses, then it would make sense to get a zoom that covers the range your likely to need.
If you like to change lenses, then probably two lenses won't do it in the long run.
You won't go wrong with the Canon 50mm F1.8. Then it's a question if you want to get a few zooms and/or primes to fill in the other focal lengths you're likely to use.
I stay in the 28m-75mm range for most portait style stuff. I use a fast 50mm F1.4 for low light situations. I just ordered a 70-200 zoom for medium telephoto work.