Boston is a coworking Mecca, believe it or not. Miles ahead of almost every other city I've visited. Here's the rundown on the major options:
WeWork: this is a national chain, and therefore it is offering nice ammenities for somewhere like Columbus Ohio. Sure the office locations are great, but there are just a few pub snacks and maybe a beer tap to check that box. You have to pay for conference rooms and phone booths, which is dumb. Overall 3/5.
Workbar: this is probably the most community-oriented - lots of tiny companies (1-3 employees), and it's a local Cambridge company. Nice patio, decent snacks and, of course, lots of beers. They very much encourage you to be social and plan events, so if you are looking to make some work friends, this is a good bet. 4/5
CIC: The CIC (formerly Cambridge Innovation Center) is the OG coworking space founded by MIT in the late 90s as a space for graduates to start their own companies next to campus. It has tons of snacks, craft coffee, plenty of free conference rooms and phonebooths, and a variety of spaces. Companies here tend to be a bit larger, and many giant companies rent offices for offsite employees. There are also lots of VCs and good networking events with free beers and stuff. Cons are that it is expensive compared to the other options, but it's one of the best coworking spaces in the country.
Cove: This is a really new, DC-based company that is in Kendall Square. They are very affordable, and have essentially a "super coffee shop" vibe with big long shared tables and lots of small things to help you stay focused. Great if you are only going to be working from the space part-time.
Oficio: This is also a Boston company which is located on Newbury street, which is great if you are in Back Bay or South End. I've only been inside once for a meeting but it's well lit and feels a lot like a coffee shop with long, shared tables. Limited amenities and conference space, but they also run meetups and events for members. Great feel in the space and affordable pricing for shared space.
Regus: Based on your description of what you are looking for, you should avoid Regus offices. They are hyper-corporate and everything costs money to use. Not a social space to work, but they have a lot of locations around town.
Your local coffee shop: Always an option, but don't overstay your welcome.
Boston Public Library: Having fun isn't hard, when you've got a library card!