[shooter210]

I think it depends on how much flexibility you are looking for and the lighting you will have as well. I use a 85 f1.8 and 50 f1.8 but have used a 17-55mm f2.8 as well. I like the 17-55mm when shooting very young kids because you never know where they are going to go and if you need to back out on your zoom. The two primes are more for set-shots where I know where they will be sitting and how many there will be in the shot. If you are using a backdrop you will more thank likely want to keep your f-stop below 4 so you can frame the subject and not have to worry about wrinkles, creases and such in the backdrop. I have done some close up work with a 60mm micro as well.