I would get the Thule 6 ski carrier. You can put 4 boards up there with mindings and 6 with 2 sandwhiched between them. I have the Thule bars up there as well. The giant full length boxes are nice too. THat is where I keep all the camping gear or boots when I take 4-5 people snowboarding.
Check out my site for pics of the 3.
http://web.mac.com/garnerbiker/iWeb/Site%202/H3.html
Thule rules.