Croatia could fit the fill - especially the Kvarner Riviera on the Adriatic around Opatija. I ahve very ahppy memories of holsiays spent walking in the hills in the morning and ending the day on the beach. Nothing like a swim after a day's hiking. This of course is going back to the late 80s/early 90s and so you'd be best taking advice form others who've been more recently re how developed it now is but the landsacpe would meet all your requirements.

But if you're looking for a really under-developed and quiet location and don't mind volcanic beaches then I'd suggest you have a look at one of the smaller Canary Islands. La Gomera has spectacular mountain scenery, you'd see everything there is to see if you hire a car for 3 days, the weather is beautful in May and apart from exploring the scenery, there's not much to do other than eat, drink, sleep and read. I should know - I go every October for just the sort of holiday you describe. Friends have also spoken hhighly of La Palma for just the same reasons and I'm seriously thinking of giving there a go this October as a change.

SM

it depends how quiet you want it, we love akyaka in turkey, there are fab mountains around, lovely beach and riverside, not very touristy or busy, a few lovely bars and restaurants, really friendly people,virutally guaranteed lovely weather, have a look at these websites

http://www.turkuaz-guide.net/gokova.html

http://akyaka.com/index.php

im sure other people will find you other gems, we also loved solvenia that is a very pretty country and we were hired a car drove around saw some wonderful places and stayed in izola. good luck

Corsica would also be worth considering too - lovely driving country (they rally there quite a lot!)

Paphos in Cyprus would be my choice. Lovely hot weather, blue-flag beaches, excellent nightlife, restaurants and bars. There's also an historical interest - Tombs of the Kings and the Paphos Mosaics. And if you fancy hiring a car for a couple of days, then that's easy too as they drive on the left as in the UK and all the road signs are in English.

Remember if you are booking for May, you need to avoid the last week as it is half-term, which equals higher prices and lots of children everywhere!

If you like the look of Ellie-meg's Akyaka, Anatolian Sky are about the only package tour operator who go there, if you don't want to diy.

Some of the smaller Greek places might fit the bill.

I suspect Paphos might be too big. How about Pissouri (still in Cyprus)? That is small with a few restaurants and no noisy nightlife.

I would choose Cyprus or Madeira not much for beaches (in Madeirs) but the chair lift from Funchal and walking in the mountains great to hire a car or use local bus services