My first 3 that I enjoyed was:
Canon EF-S 17-85mm f/4-5.6 IS USM
Canon EF 50mm f/1.4 USM
Canon EF 70-300 f/4.5-5.6 DO
This was after I started with the basic kit EF-S 18-55mm f/3.5-5.6 II and the EF 70-300mm f/3.5-5.6 III.
However, this is not the path I would necessarily recommend for someone else.
I listed them however as I felt this gave me the essential three categories for most basic situations, and even if I had to go back to just those lenses, I feel I would be able to still do a lot of what I do now.
I break these down into:
A basic walk around lens - in my case the 17-85mm
A nice prime for low light - the 50mm
Finally, a nice distance lens - the 70-300mm DO
How about instead of saying you want up to three lenses now, and to pick the other two immediately, why not start with just one, and leave a second one open for later.
So you have a nice prime, based upon what you said, I would recommend getting a nice, basic walk-around zoom. These generally start in the 15-18mm range on the wide end, and end up in the 55-85mm on the long end.
Are you wanting fast focus speed, taking in a lot of light, being light-weight to carry around, maximum versatility, best image quality, or something else? Try listing this in order of importance and this will help you decide on what you want. You can also look on the lens review page of this site and go through various videos describing the lenses. Gordon's lens reviews is actually what brought me to this site to begin with. They are a fantastic resource to finding out more about lenses.