I used the Industrial Credit Union for years (http://www.icu.org/). They offer a good rate of return on their savings plan, and you don't need to know someone in the credit union to sign up (I believe DCU has this restriction, or at least it did when I was looking for credit unions).

They are only located in Liberty Square (in the Finacial District in Boston), and they keep real banker's hours. I found both of those features desirable for a savings account, as it made me really have to put extra effort in when I needed to withdraw funds.

They do have on-line banking as well so they aren't totally isolated.

No, but I've heard good/decent things about DCU, https://www.dcu.org/index.html

They've been at 1 or 2 of the startups I've worked at over the years and seemed decent enough. But, not being a customer of them (or any CU for that matter), my opinion may not be worth the electrons it's carried on :)