Northampton and Easthampton are both very crunchy, as well as Amherst and Greenfield (which may be too far north for you, depending). There's a lot of queer mamas on MDC who live out that way, so I can only imagine there's even more straight ones... so all in all, you'll have plenty of company, once you settle in.
As for cost of living, Springfield/West. Mass is MUCH better than eastern Mass/Boston - not just housing, but things like how much it costs to park when you go somewhere, the lack of toll roads, cheaper/more produce options, etc. There's also some good CSAs out that way (sorry no details, but this is all from memory of my living there a few years ago, and other people posting here)...
Springfield itself is not exactly a bastion of progressiveness, but I"m sure there are areas that are better, as in all places!
Good luck, and enjoy your time in "the happy valley"!