Pioneer Valley Hobbies in West Springfield carries some G scale stuff, as does Time Machine Hobbies in Manchester, CT. I did speak with Dennis (owner of PV Hobbies) about gauge 1 at the Pioneer Valley Live Steamers in Southwick. G1 appears to be the province of a very small subgroup, seems to go in fits and starts. They did have a raised track for a while, I've been told it's been taken down (or moved).
Otherwise, it's pretty sparse in Western Mass for Gauge One. I've been in contact with Don Jackson (head honcho of the Down East Steam Guild) about that group...they're mostly based in Eastern MA. See the post in the Live Steam section about a recent get-together.