Iran is great if you can possibly get the visas sorted, though that can be a real pain sometimes.
Stantours should be able to help out with visas/LOIs/advice about the rest of the countries. LOIs are usually a simple process, but are just another step which takes time and money.
Also if the countries you mention are your planned route, you can probably cross Armenia off. As far as I know the Armenia-Azerbaijan border is well and truly closed and they are not very friendly with each other.
Vladivostok - Denmark 2008... Finished.
Denmark - South Africa 2010-2011... Finished.