We are going to Greece on our honeymoon in May for 2 weeks! Spending the first week via car on the mainland, and the second week, we wanted to hit 2 islands, for 3-4 days each. The first one we picked was Santorini, and are looking for a second island that is easily accessible from Sant., but also less "busy." We are pretty adventurous, and not necessarily looking for a beach or lots of tourism. Thanks in advance!
Take the ferry to Paros and right at the ferry dock catch the local shuttle ferry to Antiparos. They leave at least once an hour. Check out Mike's Place for accomodatioins: angelfire.com/super2/greece/antiparos.html
Do some searching on Folegandros, it is a short ferry ride and may meet your needs.
Naxos, Paros and Antiparos are also fabulous.
I was going to suggest Paros as we had a lovely 3 days there while island hopping around Greece. But now that I have looked at the site the prior poster suggested for Antiparos that is where I would be going.
Santorini is great - the views from the rim of the caldera are unbelievable until seen with your own eyes and a sight I will remember for years to come.
Thank you so much for the suggestions! Looking into your ideas already :)