We use the Nexus 7 tablets for work... in the industrial roofing industry. Put it an OtterBox and you should be good to go. We have yet to have one broken or destroyed. I have a couple of crews that can bend 3/4" stainless steel plate "by accident" and not know how it happened.
I use mine with GPS and the MapFactor Navigator app, works great even without the Wifi.
Aaron