I did not read through all of the replies but I thought I mention, in case it hasn't been yet, you can stay in a 1 BR at any of the resorts with a family of 5. You would have to supply your own bedding (blow up mattress and sheets) though. But if you do become a member you may also consider an owners lockers which then would be storage for the blow up...
It can be a bit cramped but possible.
Given BLT is sold out often, if you would want to be there I say stick with the obvious, commonly given advice, buy where you would want to stay. 7 mo can be hard at BLT. But then again, so can BW and BC for 2 BRs during some periods... For sure over the holidays. Dec is the toughest month to book outside of your home resort because it is the most ideal time to go for
DVC, low points, good weather and beautiful decorations...
No help here with the GV's ... sorry
But I can tell you add-on-itis is VERY REAL AND VERY DANGEROUS LOL
We purchased 180 pts at BLT Nov 18, 2009 - wanted enough for a 2br if we took DM (we have 2 dds 7 and 8) we can do a 2 br for 10 days banking and borrowing. They had a darn xmas special and ended up adding 200 AKV points Dec, 2009

I didn't even have my membership card yet and I got add-on-itis LOL
Having stayed in a 2 br at AKV it was EXCELLENT the 3 full baths were superb. DM had her on little "in-law suite" and we were able to put the kids with her so the living room could be utilized for late night TV without being stuck in the master bedroom. The layout is the same at BLT with the extra baths. I know it will be a necessity when the girls are teenagers. AKV is remote but my kids LOVED the savanah view. I know they will continue to into their teen years as well. We choose the two newest resorts because of the 2060 expiration date.