Very high level of knowledge in this thread. I thought I knew a lot about the Catskills, but Mark S. always blows me away.
One small point I wanted to add because I didn't see it mentioned. Mink Hollow (the one between Sugarloaf and Plateau) actually does have a road. Granted it has not been used in many years, but it was in fact the first road that crossed from the southern to the northern Catskills, before the rail bed and road were put in by the Fenwick Lumber company to pull wood from the Hunter area (now Rt. 214). The Mink Hollow Road started out as a bark road, then later became a logging road, then a transport road to take the hides that originated in South America and landed in Kingston, up to the tanneries in the Hunter-Tannersville area.
The road is still quite visible, and a pleasant walk, but getting hit by natural erosion. A very nice day hike up to the col. Be careful at the first stream crossing near the trailhead, this water can be 40-100 feet across and moving swiftly. 2 weeks ago we did it with just a slight challenge, but when the heavy spring rains hit, be very careful.
Happy Trails,
Tom