Give me tips on lightning-fast apple tree growth!

I've got about twenty seedling apple trees - long story short, I can't resist planting any sprouted seed. I know seedlings are a crapshoot in terms of flavor, but at least one has to be good, right?

I've also got several huge decorative crabapples, courtesy of the former owners of my property. My plan is to topwork them with grafts next spring. Since I don't want to waste precious space growing garbage apples, I figure I should pump up the growth of my seedlings as much as possible, and turn the 1 year old growth into scions. More growth means more scions means more chances to take, right?

To that end, I would appreciate tips on how to promote a ton of upright woody growth on my baby trees. I know this is the opposite of what most people want for fruiting, but I'm not trying to get a dense horizontal fruiting pattern, I want a tall stick to cut down.