We have been to both, and I would probably head towards the BC, as in March, MK closes earlier than it does at other times. Also, there is so much fun activity going on at the BW that your older kids would love, and you could relax (somewhat
) knowing they are only a walk away from your rooms! Also, a HUGE plus for us is avoiding that madhouse run to catch a monorail after Illuminations! How lovely to saunter with a more moderate crowd, perhaps sipping a beverage, as you stroll towards your beautiful resort! That is also our feeling after Fantasmic! That 10 minute walk is perfect after sitting and waiting/watching the show.