If you’re travelling anywhere between Boston and DC, you might want to check out Bolt Bus or MegaBus. Both travel from NY to DC, Philly, Boston (and MegaBus to Binghamton, Buffalo, and Toronto), and have free WiFi. Downside is that you could get stuck in traffic, but upside is that they’re super cheap (one-way to Boston cost me $16, less if you book earlier).
Bolt has normal power outlets (MegaBus has none), and both seem to have had friendly and helpful drivers both times I’ve taken it.