Well, flight prices depend on a bunch of different factors and I don't know where you're coming from. That said, have you checked out easyjet and ryanair? That would prob. be your best bet for flying between Spain and Greece....it might not be too bad...
I haven't been to Turkey or Greece but have been to Spain, Portugal, and Morocco (in fact, those were the only countries I hit up on my two month trip last year) and I will say I really believe you get it all: beautiful beaches, scenery, food, diversity, a bit out of your comfort zone in Morocco (or in Spain and Portugal, depending on who you are), cheapness (Morocco is extremely cheap and even Portugal is quite a bit cheaper than Spain)...
Anyway, if you have more specific questions please feel free to ask.