I don't know if it qualifies as lesser known, but as many of you know...
Siwanoy CC in Bronxville, NY (site of the first PGA and the only "intact, all Ross" course in the NY/CT Met area)
is one of my faves; I really think it is the finest, most challenging and rewarding course under 6500 I have ever played, and most people never play it at 6410...it's most often played by all ability levels at 6200-6300 tees.
Someone mentioned Shennecossett already, but it's been heavily renovated and re-routed over the last 40 years, still a beauty though.
cheers
vk