About the griddle, I'd go with cast iron for that. Actually, I'd go for enameled cast iron to avoid the seasoning issues with the uncoated variety.
The reason I'd go with the cast iron is that it retains heat really well so that the temperature won't drop immediately when you add food to it. Plus, if you're planning on getting a griddle/grill combo, you can get great grill marks from a cast iron grill again because of it's ability to retain heat.
Good luck and have fun!