Instant rice has a longer shelf life then the uncooked rice. I think it's about 18 months for white rice. I'm not sure about how long instant brown rice will last. Next time you're at the market, check the box. My only caveat is the cardboard boxes don't store well, so put them in an airtight bag or container for storage. It's "trail food" rather then "kitchen food" quality cuisine.

Also, consider couscous for a staple. It cooks the same but requires lots of spices (very bland). I have hydrated it with room temperature water, but it takes longer then cooking and isn't that palatable. I think it has a 1 year shelf life.