We've stayed at the Historic Powhatan in two bedroom condo and Williamsburg Plantation, also a two bedroom condo. Both places were reasonably priced (same as a hotel room) and spacious, however,
we encountered some little field mice in the unit at Williamsburg Plantation last fall. 
Apparently, field mice are a huge problem in Williamsburg during the fall months!!!
Our family likes to have the kitchen, living area, separate bedrooms and bathrooms when we travel. We eat breakfast in the condo, eat once in the park and have a late night snack/ cocktails when we get back to the condo. It helps cut down on the expensive park food.
There is a McDonalds and KFC right outside the entrance to BG. We did the meal plan at SeaWorld at Christmastime and were able to share... turned out to be a pretty good deal.
Local grocery stores and fast food restaurants may have coupons for discounts on tickets.
We've only been to Busch Garden during Howl-O-Scream in the fall but have found Saturdays to be the only really crowded day. Fridays and Sundays were even extremely enjoyable. The park is beautiful! Have a wonderful time!