If you think your kids will be interested in swimming, the villas at the Beach Club have access to Storm Along Bay (SAB), which is an amazing water experience for kids of all ages. We were recently at Dis, and my kids (ages 6 and 8) spend several afternoons there. We'd go to a park in the morning, have lunch, rest in the room after, hit SAB for a few hours and then go to a park at night for a few rides/dinner/shopping when the temp went down...and it was a wonderful resource to have with energetic kids who didn't necessarily want to spend the entire day walking in a park.
Also, if you have your babysitter there, the Beach Club area is incredibly close to both the Boardwalk and Epcot's international gateway if you and your husband want to have a date night/dinner.
Don't know what time of year you'll be there, but during our Oct. trip, buses to MK and AK were quick, with few waits (only had to wait for 15 minutes leaving MK one day, every other time, the bus was either at the stop when we went to go to a park/leave a park, or pulled up within 5 minutes).
That said...if you think you and your kids will be more interested in MK, then Bay Lake Towers or the new villas at the Grand Floridian will probably be your best bet.
We stayed at an Epcot area resort to be near family staying at the Swan/Dolphin (another option you can check out for adjoining rooms at much less cost per night than Disney's Epcot resorts or monorail resorts)...I thought my kids would want to go to the MK every day. But they surprised me and loved loved loved SAB, and Epcot, and even AK more than MK.