We LOVE Lake George!!!!!
Six Flags is wonderful-- clean and family oriented and doable in a day. That leaves you the rest of your vacation for the lake, the Fort, the outlets, the swimming and boating and restaurants and shops, and the House of Frankenstein.
Lisaross, take a Sunday mornng and go to Bolton Landing. In late August, there's always a craft fair there that's a lot of fun. (Bolton Landing is just a 15 or 20 minute drive north on Rte 9. There's also a great little outside restaurant there with an amazing appetizer--Brie in RAspberry sauce-- that I have for lunch each year.
Also, we always go the week aroung Aug 18th (Disney this year instead.) There's a Fireman's festival at Shephard's Park in town-- the kids can climb aboard old firetrucks and enjoy some jumpers and stuff. There's a little gambling for the adults as well, and nightly concerts in the bandshell. And Thursday nights there are free fireworks in town.
Also, if this is your first trip, think about an hour or so cruise on the Mini Ha Ha or one of the other ships. My son can now pick them out by the sound of each ship's horn.