LTE iPads make excellent hotspots.
Pretty much this. Tethering to my phone kills the battery and there are lots of places that don't have free or reliable wifi. The GPS also comes in handy - even if you download an offline app like Navigon or Garmin and don't use any data at all, the cellular iPad has GPS built-in whereas the wifi model doesn't. Again, using my phone for GPS kills the battery and the rMini mounts perfectly in my car.