I would assume, since you are an avid photgrapher, you want a pretty versatiel lens?  Canon makes some pretty cool zoom lenses, I am not exactly sure of the lengths, but something like  a 50mm - 105mm, or 45mm - 90mm...or if you want a slower lens, a 70mm - 300mm or a 100mm - 300mm.  It really depends on what you want to do and how much you want to spend.  I would look at Sigma and Tokina, but you are getting what you pay for...there lenses distort at the edges... the pincushion isn't too great either...but check 'em out.  Any more questions, message me.