S.F.
I've got the city-mini for my baby, but only have the single. I did, however, ask a mom who was pushing the double around in Lord & Taylor, and she said it was the "best stroller I've ever used, and I've used a lot of them!" (direct quote).
I'm a huge fan of the mini, especially for its quick fold quality. I haven't used it yet, but have tried it out a bit in the store and in my house, but my boy's still in his car seat, so it's easier for me to just use that one until he's too big.
good luck!