if you want to explore all of the island's places of interest, it could take more than a week. Overall, Skiathos is an excellent place to be. The beaches and sightseeing are wonderful, especially the Koukounaries sandy beach and Lalaria - the paradise on earth. Still, sometimes these places can get overcrowded - just in case you prefer more calm and serene places for swimming and relaxing. But the beaches abound there, so it won't be a problem to find whatever suits you, if you have a means of transportation (the bus experience can get quite tough sometimes). Megali Ammos might be a place worth staying, since it is by the sea and within a short distance (15 minutes walk) from the port.  

Environment/Nature: sheer beauty. Especially the port.

Restaurants: plenty of choice for all kinds of income, price average, some restaurants overpriced.

Culture & the Arts: Not much (as biased as this conclusion may be). Definitely pay a visit to the house of Alexandros Papadiamandis, the famous local novel writer, and do buy several of his books (translated into English). 

Accommodation: all sorts of, most of it quite expensive. Skiathos is not for budget travellers, in any case, as it is reputed to be the cosmopolitan destination of Sporades islands.

Entertainment: most of it is found in the island's central place. Not ideal, if you are looking for something elegant and charming. Noisy nightclubs in the two 'hot spots' of the island's center, packed with Greek teenagers and foreign tourists (mostly British). Cheap glamour, nothing to remind of the island's unequalled 'sexy' innocence. Profit above all. Yet there are some bars along the port, where you can enjoy your coffee or drink in the evening until very late.

Overall, nice, quite pricey, food and accommodation are good, nightlife designed for showing off.