Beautiful place!
Don't go to Skopelos if you're looking for a wild nightlife - on this island you will find a very relaxed atmosphere ofering excellent food, beautiful views and nice beaches. I would say that 4 days is enough to explore the island but I could easily stay for 2 weeks just enjoying the surroundings.
Make sure to make your way up to Glossa as well, just going by motor bike or car is a great experience.
