I agree with everyone here about the lenses. If you indeed meant the 17-55 f2.8 by canon, by all means get that bad boy. Heard nothing but great things about it. If you wanted to save a little cash and maybe pick up a flash, you could try the Tamron 17-50mm.http://www.the-digital-picture.com/Reviews/Tamron-17-50mm-f-2.8-XR-Di-II-Lens-Review.aspx


I still own mine and it works great for the kids. Just make sure you test it to see if it correctly focuses at the camera store before buying or if your buying online, get it from a dealer that allows a 30 day return policy. I missed the 15 day window so I had to send it to Tamron for the focus. Once fixed, it is a great piece of glass.


I use my 50mm 1.4 almost all the time for my kids in the house and in the back yard. I never stray to far from them climbing on things so it serves my uses very well. The other thing you could consider is the 35mm f2. It is an older model lens and makes a little noise when trying to focus, but it gives some overall sharp images and serves its purpose very well for the kids. I believe the 35mm is about $200 and you could get a 430exII for around $300 and you have a great setup for pictures.


Everyone here has great suggestions and I know they will point you in the right direction!


Jayson