In the greater Boston area, T-Mo is fine and coverage should not be an issue. Further out in small towns & villages away from the cities, and in part of Maine (true for AT&T & even VZW in ME) - coverage might be poor off the major highways when towers are far apart, offering only Edge/2.5G speed. Otherwise, T-Mo has excellent HSPA+ and 4G-LTE speed and I only loose signal on isolated stretches on I-95 driving thru eastern CT thru to NH en route to/from Boston.

The $3 per day with unlimited call/text & 200MB data daily is still offered, a best kept secret for short usage. For 11 days, you might want to get the $30 monthly plan with 5GB of 4G/HSPA/3G data, unlimited international texting (Free) and 100 minutes of voice/calling airtime - if your need is more for data. The prepaid Sim card activation kit is now on sale for just 1 cent with free shipping (MSRP is $10.00) - see here http://www.flyertalk.com/forum/trave...l#post23131544 (I usually keep 2 or 3 spare new/ones around for use by oversea visitors)