We leave in 20 days...also with a four and six year-old. For our trip in April, I brought a few things with me for the lines...DS's Gameboy, a small number-sorting puzzle, a pad of paper and pen for tic-tac-toe or hangman...but we never used any of it. We got Fastpasses when available, and we never waited in a line that said the wait time was longer than 20 minutes. Even when we did have to wait, the lines were always moving, so there wasn't really an opportunity to take anything out because as soon as we did, we would be moving again and have to pay attention to where we were going. The only times we were standing or sitting still waiting was for the start of Fantasmic, the start of Spectromagic, and for the Lion King theater to admit us in for the show. For the first two, I occupied the children with popcorn, and for the last, we had just been on the safari, so there was a lot to talk about.
This time I will probably just bring the paper and pen because it is good for the restaurants, but I will leave everything else at the hotel.
Have fun!