I've taken Business Class on the Downeaster which runs from Boston to Portland Maine. On that route it's only a $12 upgrade and I find it well worth it. Bigger, more comfortable seat and less crowded car. On the route to Maine you get a free non-alcoholic beverage too.
Thanks. It's $34 to upgrade, over the $75 base fare, on this routing, but it sounds like it'd still be worth the extra cost to us.