Suggestion: a train to West Springfield for the two weeks of the Big E. The rail line goes pretty close to the fairgrounds (but its pretty industrial), and the roads in the area can get horribly congested during the Big E. Not quite Cape Cod bridges bad, but definitely bad enough to add a good half hour plus each way.
The Lakeshore Limited is $23 to Western MA (probably varies by date like it did when I took it regularly a decade plus ago), but only runs once each way, and stops in Springfield (which isn’t too bad, but could be better).