If you've got an optimal 2v dome (e.g. A + B = 10') then you can cover it with two of the costco tarps plus one more 10' square tarp for the top. Not everyone likes tarps, but I find them to be excellent. The top tarp is left off during the day for cooling, and put on at night to keep in some warmth.

To attach the tarps, lay the long edge of a tarp along the ground and attach it, then bring the two unattached corners toward the center of the dome, folding the excess tarp to form two large pleats. The top corners are also fastened to the dome, but leave the top pentagon uncovered. Do the same with the other big tarp.

This leaves a hole in the top and actually, if you use the costco tarps, a hole where you want a door. I use one 10' square tarp on top. I attach ropes to all of its corners and fasten three of them to the base of the dome so that the top tarp can be slid over or off the hole in the top using the fourth rope as a convenient handle.

I usually make it possible to seal my dome in the event of a storm by using another smaller tarp to form a door that can be held in place quickly and easily with a couple of bungie cords.
I do most of my fastening with bungie balls, but I find I also need a collection of bungie cords and some rope for the whole shebang. A pair of tarps at costco is less than $20, and a 10x10 tarp can be had for a few bucks at a flea market. You'll spend more on bungie balls and bungies and rope. ;-)

Once it is covered this way we treat the inside too. We usually bring some carpet or cloth to cover the ground. We make sure to put bags and other stuff all around the outer edge of the dome where it meets the ground so that the wind doesn't blow dust under the edge.

Another really nice effect is to bring some bolts of fabric and hang it over the struts inside. It quiets the dome inside, offers nice visual effects, and helps create a natural insulating air layer over your head.

10 or 13oz. Duck-weave cotton from Dharmatrading.com is the good stuff. Everyone out there, using canvas, uses Cartesian fabric 2x90* instead of 3x60* (duck-weave). The stuff tears in perfect triangle by design. The pattern always depends on Nature First, Materials Second, and Design Third; in that order, but all, in equal importance. Synergy is key. I'd run arched triangles of 5, 5x3/4, and 5x1/4 triangles of the 1/2 icosa as a start. Then, work on your weaving them together. Outside-In. Duck weave is the only fabric (any material) I'd be willing to use.