Use AWESOMEARRAYS.
For a 12 sided dome start with a very long and tall isoscoles (?) triangle that is at 30 degrees...Thats 30 degrees 75 degrees 75 degrees. Cleave up from the ground to shape the dome, but leave a lot of room outside and above the dome. If you want the dome ceiling to have thickness cleave out the dome again in parrallel cuts the thickness you want it and delete the resulting ceiling sectors. Now I would have everything perfectly textured and flagged before using the pluggin. Alter the ground or ceiling...but maintain the 30 degree side atleast somewhat.
Use Awesome arrays pluggin to copy all those triangles 12 times about in a circle. It will take a while. You then multiselect everything in surface mode and hit A to adjoin them all. You can merge the center 12 sectors.
Framerate will be considerably compromised. You could try an 8 sided dome instead and use 45, 67.5 67.5 degrees for your initial triangle.
Heres an example of one, Its been chopped up to hide a lot of the outside sectors...
http://www.geocities.com/mceggtooth/DomeWagonWheel.zip