Bulk LEGO as presents I've bought a couple of bulk LEGO bundles with the idea of gathering up the identifiable sets, printing out the instructions (via BrickSet or similar) and then giving them as presents to my kids over the years along some of my sets from when I was a kid. However, very few of the sets I can identify from this big pile of bricks are complete. Some of them could be completed with the wrong colour pieces. What I'm trying to work out is a a good strategy for giving these bricks to my kids. I could give them a scoop of random bits every now and again. Or build the sets with alternative parts (but then the instructions won't quite match), or try to buy the missing parts from BrickLink/BrickOwl. Any other ideas?

There's also a tonne (well, 200+) of minifigs, I have thought about making treasure hunts to find new parts every now and again.

Slight complicating factor. My son is 3.5 and daughter 1.5, so I'll be giving him some now, but will have to keep some back for her until she stops trying to eat them.
Sorting random kits out of a bulk lot and building them can be fun, but it's often quite tricky to determine what you actually have. Also, unless you did quite a bit of sorting up front, you might find that it gets harder and harder to pick out a full kit as time goes on. You could let the kids figure it out, but probably not until they're older, and can look up inventories on bricklink. You could also make it a game: you identify a set candidate, the kids help you build it by finding parts from the lot, and if you succeed in building it you give it to them to keep. If it's a really close build, using bricklink to fill in the missing pieces would make a lot of sense. I once tried to build every single Lego kit my brother and I owned as kids and made a list of all the missing parts. I never got around to it, but a single Bricklink order might be able to clear out that list.

If, instead of sorting out official kits, you sort out the parts by type/colour, you could probably make up some nice little lots of parts that are useful for building. Maybe a bag full of spaceship parts, or castle parts, or car parts. Each of these could become a sort of "kit" on its own, and you could gift them to your children whenever you feel like it.

You could also make some little creations, or large creations, and treat them as "kits" as well. It might be possible for you to recreate the Monthly Mini Models that the Lego company gives away, or small Creator sets, or other similar kits. 

Alternatively, just spread the whole thing on the floor and tell them "Build! Share! Tidy Up After!" and let them go crazy with it.