It's about 1 mile from the BWV to DHS, so you might want to take that into consideration because you mentioned that your kids are going to be tired. You could take the boat, but it's about 30 minutes (you can cut that in half if you walk over to the S/D boat dock).
If you are looking for the easiest and fastest option, then take a taxi. It'll be about $15, take less than twenty minutes, and you don't have to worry about transfers. Otherwise, you will have transfer at some point (boat/walking to bus, bus to monorail), so allot at least an hour.