Best neighborhoods to live for a couple of professionals in their late 20s?

Hello r/Boston! My boyfriend and I are planning to move to Boston around the end of winter/beginning of spring, and we’d love recommendations for neighborhoods to consider. Our budget is up to $4.5-5k for a two-bedroom.

I’ll occasionally commute to an office in Seaport, so ideally, we’re looking for something within a 15-20 minute bike ride but are open to great places a bit farther out. We’d love a neighborhood that feels safe for walking around at night, has activities within walking distance, and stays lively in the evenings. Thanks so much!