What terrian do we need?

I'm trying to think of what sort of terrain pieces we might get a lot of use out of.  I'm not really interested in one-shot items that would end up just taking up space.   I like things that can be used over and over again (like the infinitely repeated hills, or any sort of monkey miniature).

I think we could use a few more hills to spice things up.   Maybe a few buildings with removable roofs.  A great hall might come in handy, especially one with a removeable roof. 

I'd like to fix my fortress walls.   They're pretty cool, but I totally failed to make the angled edge line up properly with one another.   I could probably use the help of a better carpenter than I (meaning anyone in the world except my wife and daughters) to shave off the longish sections.

Some sort of River or creek might be nice.   I had a two section river that looked pretty good, only it was built to span a table I no longer possess, and doesn't fit our current table.  The piece was also too thick, and you had to step up to get onto the riverbank from the surrounding terrain.

Do we need a better stockade or earthen rampart system?   We've used my cheap ramparts a billion times, and they have their flaws (though the price couldn't be beat).    The stockade I had for on top of the ramparts are long since gone.

We might be able to do a plaster-cast of the cottages I have, using the method Andrew and I learned at Fall-In,  if we wanted to try using plaster and really need more cottages.