I've never done anything worse than the upper Holt, including Huntington Ravine. But the ledges on the Brook Trail are also friction slabs (i.e. steep slabs but no handholds), not too scary on the ascent, and you can always stick to the sides and grab the vegetation.
One interesting route is to start on the Piper, take a right onto Nickerson
Ledge to Carter Ledge to Middle Sister. It is a little challenging to follow the Carter Ledge and Middle Sister trails, but you'll probably have them all to yourself. You can come down the Piper or else descend via Brook, Liberty, Hammond, Weetamoo and Piper trails if you want more variety.
They're both nice loops, but I've done the Carter Ledge route for two years running now, and it's been a few years since I've done Brook.