Having picked up some useful points on this site, thought I'd leave my own impressions for future visitors to Thassos. We stayed at the Algari on the seafront at Limenaria and found a week was enough to pack in the majority of the sites of this beautiful green and mountainous island. The hotel was clean and functional, Limenaria a good base to explore the island, the people friendly and eating out was easy and reasonably priced. A basic guide of things to do would include -

Travel - Hire a car from Speedy's in Limenaria - cheapest on the island and fully insured, 'Mr Speedy' is an entertaining guy (say Mr Osborne sent you) - 3 days was enough to see the majority of the island. You will need a 4x4 for some of the interior and anything off the main roads.

Beaches - Metalia, with its old mining factory, Paradise, with beautiful views from the sea (and a steep entrance), Aliki, unspoilt and rocky to the left, sceanic and sandy (but a bit crowded) to the right, Nysteri and Dasilio Prinos (nr Skala Prinos) with shady trees. There are many smaller coves that are worth seeking out - particularly on the south and east, just drive slowly looking for signs, tracks or parked cars. Most of these have beautiful views and crystal clear seas and are excellent for snorkelling.

Other Activities - the (steep) walk up to the acropolis and ampitheatre at Thassos town is a must - particularly in the evening. A meal out at Megalos Prinos in the interior one evening (the roof terrace at the first taverna was a good location). A boat cruise from Thassos or Limenaria. The cliff top monastry of Micheal Angelo (more impressive outside than in). Mountain biking on the off road tracks around the forests and olive groves. There would also be lots of good walks through the pine forests if you have time to explore further.

All in all we found the island very enjoyable, relaxing and picturesque, whether you were just looking for sun sea or sand, or to explore in more detail. It is geared to the tourist but still fairly quiet and relatively unspolit (although litter (and occasional over zealous taverna owners!) can be a problem in places). We found we were able to cover the majority in a week but many were happy to stay longer or come back the following year. We went to Lefkada last year and Thassos was probably just about on a par with that and we would certainly recommend it.