I know this isn't what you were asking, but we just went to the park for the 6:30pm 12/30 show at MK (bussed from RIV, no less - that took about an hour...). I know we both have small kids around the same age, and we had a blast, surprisingly.
We were so late that we only made it into the park when the fireworks started, but they are all around you, so it was a phenomenal view. We just tapped in, found a spot near the train station at Main St. and the FW started. True we couldn't see any projections but we didn't miss it at all. They do a full countdown and then it "snows" on Main St. The hub had a DJ and the whole area was a family-friendly dance party that went from around 6 - midnight. We were able to get up quite close to the castle and had plenty of room w a double stroller and we were just dancing around.
We watched fireworks 6:30-7ish, then walked down Main St. in the "snow" and did a FP in Fantasyland. We had a 7:25 ADR at Skipper Canteen, had a nice dinner there, and then went to the hub around 8:45 or 9 ish. The kids were pretty tired so we only stayed for about 20 minutes, but we had a great time and then took the bus back to RIV.
I know when we booked (VGF/RIV) I somewhat regretted not being at BLT for NYE. In retrospect with young kids I'd do NYE in the MK area, since EP is still more adult oriented and their early fireworks on 12/31 was the regular one. MK does the New Year's FW 4x: 6:30 and 11:30pm on 12/30 and 12/31.