Not as much difference as you think. There are 62 seats in Regional Business Class and 72 seats in Regional Coach Class.NE Regional BC also gives you more legroom, an in most cases, a less crowded car than in regional coach. And even if the BC car is filled, it feels less like being in a sardine can than a full regional coach car. Not to mention the bathrooms. 60 passengers vs 80 passengers does make a difference. I'll often take BC on the northeast regional during a busy travel period.From my experience, BC gets you, at least, a "free" mini-can of warm soda.
On the NE Regionals, BC got us priority boarding. At WAS, we got to cut to the front of the line that already formed at the gate, along with the handicapped. I mean, they announced something like "now boarding handicapped and business class passengers".
On the Vermonter, BC got us the 2/1 seating in the La-Z-Boy like reclining seats.