For pools of water on windowsills, or the preceding condensation on the window, a Kärcher window vac is a most effective tool. It's a sort of vacuum-cleaner-cum-squeegee, and is ever so much quicker and more satisfying than running around with damp cloths. Admittedly a squeegee and a roll of J-cloths would be about a tenth of the price.
(My parents gave us one for Christmas, having discovered them independently, but we already had one. Now offloaded to a sister. Also good for cleaning windows or shower cubicles, as is the window vac.)