Hey KY,
Those Henry books are great as interpretive guides, but I wouldn't recommend them as the best trail guides. He gets into forest ecology, natural history and a host of interesting things, so they're great for that. However, he only covers one route for each hike, and there are no large pull-out maps, only small topo maps inside. Not the best as pure trail guides.
For both areas, I'd first recommend the New York-New Jersey Trail Conference maps, if you don't already have them. They're virtually indispensable. Maps and books can be purchased at the Trail Conference site:
http://www.nynjtc.org/ They also have some book/map combo offers, and you get a discount if you join the Conference.
For guides, try Peter Kick's AMC "Catskill Mountain Guide" or the ADK Catskill Region guide.
There are some other good Catskill guides that are out of print if you can find them used, including Lee McCallister's "Hiking the Catskills"
As for the 'Gunks, I've heard good things about Jack Fagan's book, and there are several others as well. If you wait until you get up there you can check out the bookshelf at Mohonk Preserve Visitors Center for all your Gunkly needs. Whatever you go with, you'll love it up here. Both the 'Gunks and the Catskill offer fantastic hiking, climbing, xc skiing, etc.
Matt
PS Here's the Preserve site:
www.mohonkpreserve.org
PPS We're finally getting some real snow up here! As I was writing this, a little bird perched on my window sill for about a minute as if it needed a respite from the storm. Can't wait to get out w/ the snowshoes...