Thanks for the input. Final decison:
1. Yellow Peapod Plus. We figure if Jackson refuses to sleep in it, Acacia would love to.
2. Big Girl sleeping bag for Acacia. Love the Rei Kindercone and the Kelty Little Dipper but went with a cheap one from Bass Pro instead. We'll stick a big blanket underneath or pick up an alpaca skin at the market. Mmmmm, cozy!
3. Homemade for Jack. Today I scored a very nice Laura Ashley goose down throw blanket (retail $80) for $3 at my thrift store. I'm going to sew closed the bottom and half way up the side and it should be a perfect cozy sleep sack for Jackson inside the Peapod. The blanket is so crazy soft I might try to crawl in there with him. I think I can even compress it into an extra large ziploc bag. Nice!