Personally, I recommend a quiet corner of a 5 star hotel lobby/bar that has free wifi and accommodating doormen. Our first 2 or 3 weeks we camped out on the mezzanine overlooking the lobby of a not-to-be-named fancy hotel in DC (interspersed with on-sites at a nearby client's).

The best part was when the piano player started at 5:00 we knew it was about time to wrap up (and sometimes grab a scotch). That was a good way to end a day.

Libraries, however, are a great choice for telecommuting (especially when home is full of temptations for distraction).