Hi Brad. All three, for many years. Thumbnail descriptions:
Finger Lakes are lovely in summer, easy when riding parallel to the lakes, hard when crossing the grain. If you like wine, allow an extra hour or two each day to visit a winery. Most of them are high on the hillsides, rewarding your climb with a nice view while you sip and talk.
Adirondacks are, perhaps surprisingly, easier cycling than Finger Lakes. Their scenery is more grand, although nothing like the Rockies. Busy with tourists in season, better for cyclists after Labor Day if you can manage it. Even in summer, though, most of the roads have excellent shoulders, many marked as bike lanes. After riding the Northern Tier route there in the summer, I scored northern NY tops for the best cycling roads (Michigan was worst).
The Champlain Valley is the easiest riding of the three. Open to views of the lake, the Adirondacks, and the Green Mountains, especially on the Vermont side, it has the best non-stop scenery of the three. Plan on including a ferry or two in a loop ride. Fares from $2.50 to $5.00 depend on length; the premium trip gets you and your bike a one-hour cruise. Adventure Cycling's Green Mountains Loop map has routes on both sides with the customary useful information. Recommended.