Android highlights, hints, helpers, etc.
1sp = 1dp (Normal scaling) Font sizes are user adjustable (either for preference or accessibility need)
http://mobile.tutsplus.com/tutorials/android/android-user-interface-design-basic-font-sizes/
http://developer.android.com/distribute/essentials/quality/tablets.html
These assume roughly same physical/displayed height and interesting content placement. Height is assumed to be constant, although you might consider 125% of baseline height for sw600 and 150% of baseline height for sw720 to take advantage of the larger screens (adjusting content to fit those heights, of course).