My kids are the same, sandwiches just do not appeal to them. So I have invented a couple different wraps that can be eaten at room temp or warmed in the microwave.
The most famous one, Pizza Wraps. I use canned pizza sauce spread on a whole wheat wrap. Top it with pepperoni slices, green peppers, low fat mozza cheese and anything else your kids like on their pizza. My kids eat these at room temp but they can be popped in a microwave for a few seconds too.
I also do the cream cheese, ham, veggies......the kids love these too. Plain old chicken salad wraps are a hit too.