Many years ago I wrote a report on my experience to Paleochora, July 2010.
Their website doesn't seem to be set up for next year yet:

This year there was a report on the 10th edition of the tournament on chessbase:

Great tournament, experience! The following year I played in the Rethymno, also in the island of Crete, but it appears as though that tournament stopped running.

All in all, when I did my research for tournaments in Greece, I found 12 nine-round tournament taking place in the time-span of 12-13 weeks (June-September), several overlapping.
Greece is a great vacation spot but do allocate the appropriate half-days if you will be hopping between islands. Kavala tournament is also apparently still running. They split this one in sections which is particularly attractive if you're seeking norms.
It seems to me though, in a very quick search, that they don't post them on the FIDE calendar until a few months before, nothing up yet for 2018.

I played in Benasque, Spain in 2013 and also had a fantastic experience. No beach this time, on the mountains instead. There are also many 9-round tournaments happening in Spain in the Summer. Not sure how the current referendum / possible independence of Catalunya will affect things in Spain for 2018. Barcelona is definitely one of the chess hot spots in Spain.

Europe overall, in the Summer is a hot-spot for tournaments everywhere. I have enjoyed Mediterranean Europe as it's cheaper (accommodations, food, anything) in general. And it's easy to combine 2-3 tournaments if planned in advance.
Several Canadians have been playing chess in the Summer in Spain lately, sometimes combining it with a tournament elsewhere in Europe.

Reykjavik was definitely worth it. But it's in March... and I am not sure how convenient it is to combine it with other tournaments. It was still an awesome vacation, taking into account that you can easily combine it with other activities.

Good luck, and hoping to hear your own reports next year !

Alex Ferreira