Lego was a huge part of my childhood and I kept ALL of it and as the kids came along out came the Lego.
Interesting to read the comments on here and in particular the focus on the instruction booklets. My youngest boy would follow them to a T, and thats all great but I would always push the creativity of building without a set of instructions to follow.
Get the basics of overlapping bricks for strength, etc and then build using the imagination. I'd sometimes give him some minimum requirements (eg. vehicle needs to be at least 20cm long, 3 axles, has to carry bricks and of course not break in 2).
I see there is a show coming, Lego Masters. Not a fan of the host but I'll need to take a quick look at least I think