Speaking of preparing for a new school year

In our house we take a pretty relaxed approach to schooling. Not quite strict unschooling, but much closer to that than to "school at home". However, it has always been my plan that we would gradually ramp up to a more formalized approach as the kids got older so that they would be sure to cover math through calculus, world and American history, learn a foreign language, be able to write well and understand biology, chemistry and physics. My oldest son is 11 and would be in 6th grade this year. So far I have planned algebra, real science 4 kids biology, rosetta stone spanish, sonlight language arts writing program for 7th grade, some spelling and a history book. Hmmmm . . . this is starting to sound a lot like "school at home" homeschooling. I'm not sure that's really what I want. Besides, what am I going to do with his little brother to keep him out of his hair while he tackles the mountain of work I seem to be planning to set before him everyday? But how do I make sure that he actually learns something other than dragon mythology and how to beat the "Kirby" game on his gameboy?
I never really worried that my kids wouldn't learn to read, write or do math any more than I worried they'd never learn to walk or talk without tutoring. All those things are pretty much natural human impulses which a reasonably functional environment compel a kid towards any how. But studying algebra or learning what a golgi apparatus is? And my 11 year old is has a pretty stiff streak of laziness going on these days and I'm not sure if his natural curiosity would be enough to motivate him to get up and find an answer to something he's wondering about rather than lay on the couch contemplating building the ultimate dragon costume for Halloween this year. And what if all those people who say a more relaxed approach will result in lazy undisciplined children are right and I've erred in not being more disciplined and structured up to now? But then again, he actually has expressed an interest in a more serious study of biology and thinks he's pretty hot stuff for being ready to study algebra. Maybe I'm not giving him enough credit. And the Rosetta stone is supposed to be pretty easy to use and kind of fun and if we can all learn to say funny things like "Karl Rove is laying down under the airplane - he should eat more salads for lunch" in Spanish, that might be motivation enough. Plus the writing program is only a 2 day a week program and the world won't end if he throws some historical novels into his reading repetoire and saves a more serious study of history until he's actually interested in it. Plus, he still wants to make a website and possibly a video game devoted to dragons (what else?) and I really don't want to take so much of his time doing the "proper" academic things that he doesn't have time to pursue that. Or plan the fort his dad and I promised him we'd help him and his brother build. Ack!
I'm sure we'll stumble through to a balance that works for us, but if any more experienced moms have some relevant words of wisdom to share, please do.