Sounds good to me on whatever troops/figures anyone wants to add. I think that the more variety, the better - which is why I love the freedom in these Customizing Challenges. So much fun.
I am updating now to reflect my example of how to make a foamcore diorama - and it doesn't have to be foamcore, whatever materials you want to use are fine.
FOAMCORE MODULAR DIORAMA
Base Piece -
First of all, I used a large piece of foamcore and painted it, burned it some, and cut other shapes for debris and hot glued them on.
Wall #1 -
Then for the primary wall, I made two sides to it, making it a 3-dimensional piece for durability and realism, glued the pieces together and painted/weathered/added greeblies to it.
Wall # 2 -
Used the same technique as Wall #1, but wanted to keep the same length but different heights, adding variety but making them stackable to create more possible looks to them. Both sides painted again for more possibilities.
Wall Bellies -
Then here is an underside shot to show that they have a built in support system for durability. Remember to use a glue gun heavy here where you can't see the glue.
Just a small building added for effect.
Modular Shot -
And a random setup with the pieces. Could be used in many different ways.
Hope this helps give some ideas!