If you have pins 3 and 4 available, they're always reliable for me. Any GPIO can be used as an interrupt, but there are many possible contentions to look out for if you plan on using any of the other hardware blocks.
For example, spiffy 1 uses p32 and p33. Spiffy 2 and PUART are configurable, so, if you plan to use them plan out which pins will be used for what. (there is also some interdependence between spiffy 2 and puart, but don't be concerned with this if you don't plan to use either one )
The final thing to allot pins for is an external clock if one is used: this will use up p11/12.