Nine Hands
Explorer
It all depends on the situation. At the gaming store I run at, there is a really decent sailing ship model (3 levels all done in 1 inch hexes), so when running an encounter on a ship, I use that. We had a fight once in a field, and I saw a huge piece of wargaming terrain that matched it, so we grabbed it off the wall and ran the encounter there (using a ruler and eye balling the rest). Other times I use a regular battlemat. It all depends on what is around the store at the time 
