Seattle is very "green" territory, so I'll throw my perspective into the mix. A lot of the new hip/green moms around here would be very into wool batting. It's really nice to work with too. And while pricey, not as expensive as bamboo batts.
I guess it really depends on the individual couple as to how well they would like a baby quilt made out of recycled clothing from a thrift store. A lot of new parents are a little on the squeamish side when it comes to anything used touching their newborn (not as big an issue if it's from a family member). So you'd have to be the judge of that.
RST