Hi,
you mentioned they are interested in Iceland.
I was there in Oct a few years ago, and had a fabulous trip, but it is cooooold! Each day I wore everything I had brought with me - two pairs trousers, 3 t-shirts, 2 fleeces, and was still cold.
However if they are well wrapped up, its well worth it. In one day we saw geysers, a frozen waterfall, looked into a volcano, saw the aurora borealis. If they like nature and unusual landscapes, they'll love it.
Reijkavich is VERY expensive - about 12 euro for a glass of wine. But if you are only there for a weekend, it shouldnt add up too much.
Ragazza.