My SIL is going to watch our twins in September (they will be about 15 months) while DH and I attend a daytime wedding. SIL would arrive about 10:30 so we could get to the 11am ceremony. They will put the kids down for a nap around noon. This will be her first time watching the kids without us there. (I assume she is bringing her husband with her of course.)

I wouldn't pay her like a teenage babysitter but want to do something.....

I figure that I can get subs or something to leave in the fridge for them to have for lunch. What else is appropriate?