The 1br @ BLT sleeps 5. You can only get one promo. Expedia's rate is likely the summer room only discount which would then prevent you from getting free dining. With a family of 6, you need at least a two bedroom or a cabin at the Fort or a family suite at the ASMu. I do NOT recommend the ASMu suite. Bus transportation was horrendous there. I have stayed at the Grand, which shares busing/monorail/boat transportation with the other Deluxe resorts. It was wonderful! I haven't stayed at the Fort.
There's a PIN code right now, which would save 40% off the rack rate for a Deluxe. Depending on how old your party members are, the Free Dining or the 40% may be the better deal.