Wow man, there is so much Boston for you to experience. if you are dedicated in truly exploring them I won't even make a suggestion. Just please keep going!
The first album is amazing and legendary, the second album is a bit hit or miss, A Man I'll Never Be is, for me a highlight, one of their best songs. Their third album, Third Stage, which Cool the Engines comes from, gets overlooked a lot, it definitely has more of an 80s sound, but personally I love this album. They were a bit older and wiser, and there's some pretty deep life lessons and philosophy coming from these lyrics, it's not really the party album like their first one, so I think people dismiss it for that.
Many of the songs on their debut album were written in the early 70's, while the album was recorded in 75'-76' and released in August 76'. Nobody had sounded like them before, or since.