I agree with Natdencro. You guys are great to remember the folks who work with your kids. But then I've noticed that DisBoarders are a VERY thoughtful bunch.
When I asked my DD the tip question for someone else she said :
"I work with 3 and 4 year olds, I'm easy to impress."
For the counselors, the recognition is as important as the amount. They are salaried and don't count on tips as part of their compensation. But the recognition really helps morale. One thing you could do as part of your preparation is to help your child decorate make some custom "note paper" to take along so you could write a brief thank you for the counselors that work with them. Just an idea. Then if you choose to include a gift card, that's a plus.
FYI, She hasn't said anything about Target but has mentioned Wal Mart.
Also, if any of the counselors do a "MAGICal" job, be sure to mention that in your evaluation. They get recognized within their department if they get named in a positive eval.