We go there all the time, but I have relatives in Richmond, so we only stay the night when we splurge for a single night at Great Wolf lodge which is an exit up from Busch Gardens.
Busch Gardens itself is great for little kids. Not only do they have Sesame Place, but they also have a kiddie area in Ireland with a Dragon theme and lots of water areas there for the kids to play in during the hot summer.
We've never been to Wet n Wild, Busch Garden's water park, but I've heard great things about it. We got annual passes through Sesame Place in October. If you're driving down, I'd suggest checking out the actual Sesame Place in Langhorne, PA on the way down. It's ONLY for the little ones, it's really a cute little park, and if you feels it's close enough for more frequent visits, get their annual Grover Pass (which is 25% off at $157 until March 1st). It will allow you to also get into Busch Gardens and Wet n Wild under that same pass. Sad that your Disney trip is cancelled, as it also gets you into Aquatica and Sea World!
I was telling someone on another thread, there is also a great zoo they'd enjoy called the Metro Zoo in Richmond. And if you go a little further down Rt 64, you'll be in Newport News, where they have a cute children's museum, butterfly gardens and some waterfront areas. I'm sure there are good accommodations all around that area.
Hope this is helpful!