Well, finding an urban-ish vibe in Mt. Kisco might be a stretch...
But to at least give you a starting point - check out this website:
Quality Star / Child Care Council of Westchester, Inc.
They list all of the state licensed daycare providers in Westchester - home based and centers. FYI, it's a really clunky search mechanism, so if you don't search correctly, you may miss some places. Try a few different queries just to be sure.
I live in southern Westchester now, so I can't comment on specific options in the Mt. Kisco area. The closest I looked at was Ann and Andy in Elmsford - they were really lovely. A lot of elementary teachers send their kids there. But that would probably be a real hassle for you commute-wise.
And my guess is daycare is just as expensive here as in Cambridge. In Westchester it seems to run from $15,000/year up to 25,000 depending on if you do home based care vs. a center. Montessori-based programs seem to be the most outrageous in terms of expense, with corporate outfits (Bright Horizons, etc), close behind.
And just a question - IBM doesn't have onsite daycare? It's such a lovely large site, you would think they could have put that in at some point. Especially given the fact that so many couples seem to work there. At least that was the case when my father was working there as a computer scientist. I loved going to visit him when I was little - your girls are going to have a blast doing that as they get older. It's such a cool building, with all sorts of neat things to look at in the cafeteria and as you walk the halls.