To be totally honest - I aready raided the Units section of this forum and collected some art that might be useful.
Unfortunately I am not as fluent in Civ modding as I want to be, so if any kind of feature is not possible then we should think of something else. Here's the general idea:
Three Houses are fighting for the planet of Arrakis, also known as Dune.
House of Atreides - generally peaceful peoples, but with their own twist on arms, since they are somewhat descendants of Harkonnen. Their leader is called Duke - either Duke Leto Atreides or Duke Paul Atreides - whatever)
House of Ordos - (introduced in games Dune 2/Dune 2000, have no idea where they came from, but let them be) simply "other House" with it's own ties. Since there is no mention of it in books we can be as creative as possible about this one. Don't know what the leader is called, we can think of this later.
House of Harkonnen - mean war machine. Always have heavier (and more expensive weapons), nastier and more brute. Bad bad guys

The leader is called Baron Vladimir Harkonnen - big fat mean guy.
The setting and some historical details - all three Houses arrive at Dune with their MCVs (Mobile Construction Vehicles - analog to settler), as Emperor Shaddam III allowed them to compete for Dune, home of spice (melange) by harvesting and fighting. Whoever wins - gets the planet and, therefore, becomes the only provider of spice to the whole world. Spice is produced by Sand Worms (also called Shai Hulud in native's tongue). The native population of the planet (called Fremen) worships Shai Hulud, but also makes a good use of them as means of fighting and transport. They are technologically challenged but get by using stealth and knowledge of their home planet.
Other important details I think worth mentioning:
- given that 90% of the planet is covered with sand there has to be some changes in the rules as per collecting spice and water being the only two major resources of the game.
- each House must have their own unique units unavailable to others
- some of the units should only be available from certain buildings, so if that building is not present in the city the unit is not available
- having some buildings in the city must prevent having some other buildings in the same city. Discovering some technologies must prevent discovering some other techs. For example - given that you have Tech1 you can research Tech2 OR Tech3, but not both. Also, since some units will depend on the researched technologies, this will give Houses even more uniqueness (hope I spelled this right).
- if possible, I'd like to have some units to be "purchased only", meaning no House will be able to build them, but only purchase from sertain buildings. Also, some of the buildings must be unique, like Wonders, that could be built only in one city, but available to all Houses, so that no House would have more then one of such buildings.
If that's not scaring you, guys, away, then feel free to donate more stuff. I'll try to post buildings and units line-ups shortly.