As you're a pet owner, I'm sure you know how much of a pain finding a suitable hotel can be... but thankfully Boston isn't a city where the best simply aren't up to bar, and one of the city's finest offerings, Marlowe, A Kimpton Hotel, is both pet friendly and very posh.
Mood is everything when picking a Casino. Forget the hottest slots or the cheapest meals, make sure you have a clear idea of the atmosphere you want, and chose a casino that also matches your wallet. The Borgata has a classy atmosphere that can make for a great segue into maturity, but it comes at a premium. For something a little more wild, try the Harrah's Resort.