Busch Gardens Williamsburg (now called busch gardens europe) is AMAZING. It's by far my favorite amusement park-IMO 100x better than Busch Gardens Africa (tampa bay). If you're only going for one day, I suggest you make it an all day thing if you can--there is so much to see and do.
General Rides: For both kids (and you!) Don't miss Corkscrew Hill--simulated minimal motion ride/movie-not a coaster but very entertaining! My son was 4 when he 1st went on it and had a ball...right next to my 47year old father who had just as much-if not more-fun.
Also Curse of DarKastle--very similar to Spiderman in IOA as far as motion and effects go.
Sky Ride offers not only beautiful views, but a chance to get to another country while resting your feet. Note that it's not a round trip.
There are also smaller attractions throughout the park-Tea Cup equivalent, that Viking ship type thing, etc.
Escape from Pompeii is very fun as well-I didn't list it as a water ride, because if you sit in the middle, you won't get more than a drop or 2. Excellent special effects, more than a splash ride.
Water Rides: Roman Rapids is fun but will get you SOAKED (I'd liken it to bilge rat barges).
Le Flume we usually pass by, it's a run of the mill log flume ride.
Coasters: Alpengeist and Apollo's Chariot are my personal faves. Apollos Chariot is actually where Fabio got hit in the face with a goose, lol. Alpengeist is a suspended coaster, and Apollo's Chariot is a more traditional one, but with only a lap bar-no harness.
I haven't tried the Griffen, but will later this month when i go with ds.
Lochness (traditional upside down steel coaster) and Big bad Wolf (suspended cars) are also very good
Shows: Pirates 3D and the Magic Show in Ireland (forget the name!) are both very fun for adults and kids.
To Eat: Trappers Smoke House is great-smoked/BBQ foods. I don't remember the cost, but a sampler (I'm thinking around $12 or $15?) fed me and my then 17 year old sister--it has brisket, ribs, chicken, fries, and a roll. My then 7year old son loves it too. It's counter service with a large outdoor dining area.
OR, since you're doing a day trip,
das Festhaus has mostly German and American foods, also counter service but with huge indoor seating--time it right and you'll see a free show while you eat to make best use of your time and get out of the heat. (refer to the maps)
For Snacks: Caramel Apples in the Sweets store in England (entrance) are amazing-fresh and juicy. The Brownie Sundaes and rootbeer floats are also great-found in most snack shops throughout. Street vendors also sell those huge turkey legs. In Italy, the Italian Ice vendor is great-seems pricey, but you get a HUGE scoop-again, my sister and I shared, with some left over. Plus the usual fare-churros, icees, pretzels, etc.
Tip-If even a drop of rain falls while you're there, go to customer service, they'll give you a free pass for the next day. At least, they still were last year as late as october.
Tip- They've never stopped us from taking a water bottle or a few juice boxes in with us. The only time they've stopped us was when my genius sister was trying to bring in a sausage egg and cheese buscuit from McD's that she had just opened.
Tip- Speaking of the egg sandwich, there are TONS of places to eat within a 10 minute drive from BG-anywhere from McDonalds/Sonic/Wendys/KFC, to Hooters, Golden Corral, fancy restaurants (someone else will have to help you here-I'm a budget mom--it's usually Sonic and Golden Corral for us!), etc.
Tip-The grounds are beautiful (award winning, actually) and meant to be enjoyed. There are TONS of photo ops, with old looking buildings, bridges, lakes, rivers, rides, flowers, animals, fountains, etc. Having said that, wear comfy shoes.
Have Fun!
Kelly (who looking back on this post, thinks she should write a book about BGE!)
crappiest $100+ dump i've ever seen.
I loved the Alpengeist coaster. There were some strange coasters too, seems like one was called big bad wolf that kind of swung you around. 
). I've never seen them quote over $69/night.
but lets pick on him for now!).
