If you've only got two weeks, I would be inclined to go Kithnos (Loutra harbour on the NE side); Ios; possible diversion to Thira/Santorini (marina on S side at Vlichada); Astypalia (new sheltered harbour there); Nisiros (must see the volcano!) and then up to Kos. That route
should be on a reach all the way. Alternatively, from Ios you could go Amorgos, Kalymnos (both good harbours in the meltemi) then Kos. Details on all these are on the World Cruising Wiki. I'd be inclined to avoid the Serifos, Paros, Naxos route as the harbours are tiny and/or packed during the season. Good sailing!