March is tough. Anywhere north of Poughkeepsie still as a good chance of snow. What are your interests? You might like a stop in Lake Placid if you're interested in winter sports. Visitors can ride on the Olympic bobsled run, skate on the Olympic oval, and more. If you are interested in art, you might veer east a little and visit Mass MoCA in Pittsfield, Massachusetts. Just north of Poughkeepsie, Hyde Park features the historical homes of Franklin D Roosevelt, Eleanor Roosevelt, the Vanderbilts and more homes in towns nearby.

Just a quick update to ellenem's post, Mass MoCA is in Williamstown, north of Pittsfield.

I thought it was neither - I thought Mass MoCA was in North Adams.

Almost exactly halfway , via the NYS thruway, is Saratoga Springs. Lovely area, but in March??? Albany is a little bit south of there, and I imagine you could find enough to do and spend a day or 2 in Saratoga/Albany even at this time of the year.

Burlington Vermont is a bit of a detour, but is a more vibrant year round city.

Rhode Island is not really "in between" Montreal and NYC, but since you asked, Providence is a nice small city, with a college town feel and busy-ness. Newport is a fabulous place to visit--less so in March, but still worth a trip if you have no other time of the year to do it.

ding ding ding ding ding ding...
We have a winner!

I thought Mass MoCA was in North Adams.
http://www.massmoca.org/directions.php

Williamstown is not too far away, and the Clark Art Institute is there.
http://www.clarkart.edu/

My friends live in Pittsfield, thus my attaching my visit with them and Mass MoCA . . . close enough anyway to give the OP an idea.

Wow, my mind is spent today. I was thinking North Adams and typed Williamstown.

Mid March is spring break for my son in upstate NY, we would like to do some sightseeing, and I don't feel like traipsing all over with ski gear, we've got good skiing in California right now, and we like to drive(not in snow)around as long as it's in the direction we are headed. Keep the suggestions coming please.

Well, it's not usually thought of as a destination city (and shouldn't be, lol but if you want to stop somewhere you haven't been, Hartford CT has a few sights. The Capitol with it's connected Legislative Office Building, the Wadsworth Atheneum, Bushnell Park, the Mark Twain House and Harriet Beecher Stowe House, West Hartford Center (a fun town to walk around), Elizabeth PArk if you're lucky and have good weather. If you're there on a weekend there are some good entertainment venues too. Downtown Hartford, tho', is a dead commuter's city, so I wouldn't stay there or plan to spend time there.