Those look great, I keep wanting a desert setup for myself, and that might just be the way to go about it. I keep telling myself I will just sell some things and put in for an order from Crescent Root, but I keep not listening..
One thing you might consider, if you base your models on steel washers is using magnetic stripping for the stair treads, that way it is much easier to place models on the stairs. The way you have them looks to scale and grand, but it irritates me to no end as soon as I build something as such, and everyone wants to have models halfway up here and there.
Ryan