Looking for a room in the cities.

I am looking for a basement or room that has ready public transit access. I am a single professional man in my 40s (I work in communications) who is likely moving just suitcases. I really just need a decent room in a decent neighborhood with good public transit access. Please let me know what neighborhood. I am open to either a weekly or monthly arrangement, but weekly may work better for my time I am likely going to need a place for 2-3 months, but due to my work I can't pinpoint the length of my need. As far as my personality goes, I'm pretty quiet and keep to myself. I'm always working on writing projects, reading, rewatching my favorite shows, and watching sports in my free time. Definitely not a big partier.