Fixing some rotten wood, what type of wood should I use ?

We've decided to just go ahead and take all the metal off the front end and take out the front window. I'd feel better as then I'd know if any other wood needs replaced or repaired. I can order the metal thru a place in Elkhart. It's about a 3.5 hour drive to go pick it up.
This Saturday will be the tear it apart day. I'll try to remember to get some pictures of what I find once it's apart.