T-Mobile isn't about to stop tweaking its phone plans any time soon; in fact, it just overhauled three of them with data in mind. To start, you'll get twice as much full-speed data on your phone plan if you add a tablet to the mix from September 3rd onward; if you currently get 3GB, for example, adding the $10 monthly tablet access fee will give you 6.2GB (including the 200MB of free tablet data) to play with. It's potentially a much better deal than what rivals offer if you intend to use your tablet a lot while on the road. On Sprint, you'd be paying $75 per month for both phone service and 4GB of shared data.The other plan changes don't necessarily give you as much data, but they may be a better value if you're cost-conscious. If you're on a $40 Simple Starter plan, an option arriving on September 3rd will let you pay $5 more per month to quadruple your max-speed data from 500MB to a much healthier 2GB -- not quite as good as Cricket (which delivers 2.5GB for $45), but close. Whole households, meanwhile, can put as many as 10 lines on a family plan as of August 27th. It still costs $10 per person like the previous five-line option, and everyone gets their own data. Sprint currently has the advantage in family plans if you're only looking to get as much data as possible for the money, but T-Mobile's expansion may be handy for returning students and anyone else who'd rather not shoulder the full cost of phone service.