A dream vacation, but my wife would insist on Hawaii first.
There is ferry access to Vestmanneyjar (sp?), home of Eldfell volcano (the one that almost plugged the harbor when it erupted on the city limits) and Surtsey from Thorlakshofn, which is west of the map boundaries. It's a 3-hour ride; I found some pictures of the trip via Google, pretty spectacular if the weather is good.
I've already got my "Learn Icelandic" CD. Give me six months and we are a go. We could go to Hawaii for the lava tubes first. The cost of airfare are about the same I think.
My hubby wouldn't care which one as he prefers Volcan Arenal in Costa Rica.
Hawaii is "ice"land.