What Island Should I See?

I'm gonna be staying in Panteleimonas, it's at the northwest end of the Agean Sea. I was planning to visit one of the main islands, like Crete or Rhodes, but they're too far and too expensive. They have a trip to Skiathos for 45 Euros, but it's over a 100 miles from where I'm staying. It's gonna take forever to get there. I'm not sure where thy're sailing from. What about Thaos? It's a little further from Skiathos though, and once again the problem is getting there. These are only day trips, so it's probably gonna dock at some beach and I won't have much time to see the island. But I can't come to Greece without visiting an island. Is Skiathos a good choice? Once again, I didn't get to read where the ferries saile from. If it's from Saloniki, it's gonna take forever.