Palazzos is the best bar we found in Sidari! The bar staff are a great laugh (there's 2 George's and a girl called Laurie). We really got to know them and got lots of free shots and drinks, had a great laugh every night we went. The music/DJ is very good too. If you like Cocktails, ask for a "Baby George Special"!
Just got back from 2 weeks at Stema 1 apartments, they are really good! The Stema 1 are really good, so Stema 2 must be excellent! (Think they have air con). The owners and staff are really nice people, they do some good food too. As far as we could see, everyone shares 1 pool, but its really good. Only 5 minutes walk from the town but its nice and quiet.
Aqualand is great for any age! My girlfriend and I are both 19, but had loads of fun. Some of the slides are very extreme and fast, something for everyone! Book through a travel agent in the town (the one opposite the 3 brothers hotel is best) because the reps charge lots on top. You should be paying around 17-20 euros. Well worth going to