Rafters 30" to 35" O/C sounds odd. What do you have for roof sheathing that spans that far? Do you have cross blocking 16" or 24" O/C? If so, this could create a problem for venting above the fiberglass with "vent keepers", as they would block the airflow from soffit to ridge. Your best bet is probably a "build down" to maximize r value and venting. You need ridge vent and soffit vent and air space between ply and batts/blown. See this article (2 pages long): http://www.jlconline.com/jlc/archive/energy/cath_ceiling/index.html
You also need to confirm that your floor framing is up to the task. Jay is right, your homeowners insurance would not pay out if your attic joined your bedroom b/c it wasn't framed right/permitted with the town. What about heating/cooling? I would think this should probably be a separate zone for heat/cool. You'll be sorry if you don't fully anticipate these needs before the drywall goes up. Remember, if you have hot air heat that a return duct is as important as a supply duct. Also put in plenty of phone/catv/network wiring as your kiddies will need it before long.