I'd vote WL because three of the kids are 5 and under and, realistically, won't get much out of SAB yet.
First let me politely disagree with this. We think that SAB is particulary good for kids in the 2 to 5 range. We've been there with several of our own in that very range, and there is an entire section of the pool complex dedicated to little ones. It has several sand beach areas, one of which extends into the water, which goes from zero entry to a depth of only about 2 to 2.5 feet. It is a great area where the kids can play in the sand and run into the water and wade around without getting into trouble. You still need to watch them of course, but it is a great area for them to play in. It is one of the best pools areas in all of WDW for the toddler crowd, IMHO (and we've been to most pools on property). The Wilderness Lodge is great, and the kiddie pool there at the main pool area is one of the biggest on property, but SAB is a lot more fun for kids ages 2 to 5.
That said.......how long is this trip going to be? With a large crowd it might be a logistical nightmare, but we seem to split all of our trips now between the two resorts, spending half the nights at BCV and half at VWL. Changing resorts with our family of 5 is pretty easy. We even made it work with a Grand Gathering of 11. We just can't decide between the two resorts any longer, and by switching resorts you get to take advantage of the benefits each has to offer. We plan most of our Epcot/MGM time while we are staying at BCV (being able to walk to both parks is great), and then focus on the MK while at VWL (the boat to the MK is wonderful).
If you aren't adventurous enough to attempt a switch, I might recommend BCV for a large party, especially one with more adults than kids. For the kids you'll have SAB, and they will love that. Access to Epcot is so easy, and not only is it a park that the adults can really enjoy, given the ages of the kids they will really like Epcot as well. Boat to MGM is really nice. You have access not only to all the restaurants at the YC/BC, but you can walk to the Boardwalk as well. The Epcot resort area just has so much variety to offer to a large party that it is a great choice.
Do consider trying both resorts.....you'll give your party a taste of the two best resorts on property and you'll doubly WOW them. But if you can't do that, go with BCV.