The Hartford/New Haven market used to include Springfield until 1997 or so, with an overlapping market existing for the Pioneer Valley which still exists to this day. I've never had a cable provider give us any out of market stations except WGBY and WNET. New England has some weird market overlaps. In southern Vermont cable systems will provide stations from Boston, Springfield and Albany. Cape Cod and the Islands gets Boston and Providence stations. Thus you end up with two or three affiliates for the same network, each with different syndication schedules and all showing identical network programming. It's a mess.
Brattleboro, VT is in Windham County. It's the northwest fringe of the Boston/Worcester DMA, likely due to viewership patterns. I personally think they should be part of the Burlington/Plattsburgh (NY) DMA, since Montpelier is the capitol there, not Boston. Brattleboro is usually paired with Keene, Cheshire County, NH (about 15 miles to the east) for radio purposes. Cheshire County, NH is also in the Boston/Worcester DMA and is home to WEKW-TV (PBS) channel 52. Go one county west and you have Bennington County, VT. That's in the Albany/Schenectady, NY DMA. Last I checked, Comcast (formerly Adelphia) in Brattleboro carried WCAX-TV channel 3 (CBS) from Burlington. I think they also carried WCDC-TV (ABC) channel 19 from Adams, Berkshire County, MA.
As for the Springfield/Holyoke, MA DMA, it's always been Hampden, Hampshire and Franklin Counties, MA (i.e. Springfield/Holyoke, Northampton and Greenfield, respectively). They imported CBS and FOX from Hartford for years until "CBS 3" and "FOX 6" came along. "CBS 3" is a low-power digital station while "FOX 6" is actually WGGB-TV channel 40-2 of Springfield.
As far as I know, WNET-TV was never carried in New Britain. Channel 5 may been carried years ago in their days as independent WNEW-TV. Channel 9 and 11 were definitely carried here. So was channel 38 from Boston. WGBY-TV (PBS) channel 57 was the only Springfield/Holyoke market station I ever saw here.