Have you considered staying in a 2 BR at OKW instead of BWV? OKW's 2 BR will give you a lot more room than BWV, and with your group size you might really appreciate every square inch! OKW has a much larger kitchen, dining table, lr and laundry room then any of the other DVC resorts and the 2 nd br has 2 queen beds vs 1 queen bed and a sleeper sofa. All these things will come in very handy with the # of people and the age make up the group you have.
OKW will not be as conveniently located to parks, restaurants, nighttime entertainment, etc as BWV, so you will have to either take a bus or drive vs just walking to many things but the trade off of convenience of location for larger units will be greatly appreciated by your sized group. 8 people in an OKW 2 BR is definitely do-able, a little cozy but fine; 8 people in any other WDW DVC 2 br is pretty crowded, especially if you have 4 kids. I would also strongly suggest having at least one car if you stay at OKW. OKW has only bus service to everywhere but DTD, and though the bus service is fine it is a lot more convenient to have a car. Other than AKL, OKW is definitely more removed from the major park/dining areas than the other deluxe resorts are.