Hellboy, take a look at the site DB for Dom3 (link in sig), that should give you an idea of what sites to find in which terrain. A lot of sites are "Any land", but in general the tendency is:
- Fire: waste, mountains
- Air: mountains, plains
- Water: swamp, other non-waste
- Earth: mountains
- Astral: any, slight emphasis on plains
- Death: any, slight emphasis on mountains
- Nature: forest, sea
- Blood: any
I'll be updating the site DB in a few days because I now have all of the info I could possibly need, thanks to DrPraetorius. His efforts have given me accurate terrain masks, site frequencies and quite a few other bits of info that helped me track down some errors and add missing things to the DB. I'm also going to shamelessly steal his formulas for displaying the specific terrains and uniqueness of sites (using the terrain masks as basis) to make the DB more readable. That way the DB will be easily accessible and only the hardcore enthusiasts will need to try and decipher his data dumps.