Your kids are six and three now, which will make them at least seven and four (and maybe eight and five) by your travel date. There is a huge difference between a tentative can't swim three year old and a daredevil swim like a fish independant eight year old. Only you know the temperment and likely developmental changes in your kids in the next year.
VWL - Great theming, easy access to the MK via boat (very important at the tentative three year old age - if your six year old is still a Dumbo girl at heart, it may still be your favorite park), a nice pool with one of the tamest waterslides at a
DVC resort. Plus you get good access to FW as well - HDDR, Petting Zoo, movies... Not knowing your kids, this would be my blanket recommendation.
BCV - Wonderful access to both Epcot and MGM - MGM is a particular draw for thrill ride fans, good access to the BW for the nightlife and restaurants. Biggest plus (and biggest minus) the incredible Storm Along Bay, a pool that will ensnare your children, but may (depending on how well your kids swim and what kind of parent you are) have you tearing your hair out or avoiding the pool. It does, however, have DVCs only (TTBOMK) kiddie slide, a wonderful zero entry pool, and great sand.
BWV - Our home (disclosing conflict of interest). A nice, but rather deep main pool with a challenging but manageable pool slide, but unlike SAB, you can sit in a pool chair with a rum drink and see the whole thing. Busier than BCV with the same great access to Epcot and MGM (Epcot is a little farther, MGM a little closer if you walk it). Boardwalk activities that run all night - Disneyfied so they are kid appropriate - although late night traffic out of ESPN or Jellyrolls may be something you want to have the kids asleep before it happens. Community Hall. I think this is a better resort for adults and teens than for kids (although we have preschoolers - we really bought thinking long term, my husband and I like Epcot best), unless you want the Epcot/MGM easy access and want to avoid SAB. Some chance of both Standard View rooms (the Epcot area park access on cheap points) or Boardwalk View (guarenteed now, and something most people find desireable) at seven months.
OKW - Access to everything is via car or Disney transportation (you can boat to DTD), but if you drive everywhere anyway, the ability to park in front of your unit will make this more convienent than less. Larger rooms than the other DVC resorts - nice if you are planning lots of time in your room (and plain old just nice, but particularly attractive if you are spending a lot of time in the room - or putting the four of you in a studio or one bedroom). Plus, cheaper points - so a real value if you are looking to save a few points. We have yet to see what the slide will be like here.
SSR - Will have good access to DTD, but the park access of OKW and it doesn't look like you'll be parking in front of your unit to make up for it and standard room size (but, although the points are higher than OKW, they are still cheaper than the other resorts). We will have to wait for the pool to open up to judge the quality for kids (pool slide quickness and complexity, pool depth, and the all important "ability to watch your children from a pool chair"). The do seem, however, to be planning a very "family friendly" approach to food - I think of it as more deli style - i.e. the ability to pick up something on your way back to the room to eat or throw in the oven. Does have the cool factor of the "new resort."
Whatever you decide, book your home BCVs before seven months. That way you won't fret on any wait list and will definately have a place to stay. Someone reported that according to MS, VWL is the hardest to get into at seven months.