Just completed building a loft for my kid.

[*bfine32*]

Nice so far and being able to work with wood allows you to customize. Here's what you need to do next to give him a true space:

Put a piece of 3/4" plywood on the top of those long posts

Get a small TV wall mount and mount a small 19"ish flat monitor to it.

Add a shelf to the top where he can put a video console/DVD player

Connect all by running the wires above the top

Enclose the 6"ish gap between the top and the ceiling.

Win dad of the year award.