It's all really very nice, pretty marina, 45 min transfer from Thessaloniki, excellent kids club. We really liked it. Agree it's not the real greece but that didn't put us off and we would probably go again.
To break it down ...
a) Sani Asterias Suites - on the marina where all the restaurants are, top end, serious 5 star luxury, only 50 suites or so, very lovely - also pricey. If you can afford it, I'd go for it!
b) Porto Sani is next - near the marina but no actual sea views, it's set slightly back in gardens, also really lovely and luxurious, slightly less expensive than Asterias, maybe 200 suites.
c) Sani Beach Club - not on the marina either a free resort bus ride to get there or a 20 min walk. Much more affordable than asterias or porto sani but still very good. Low level bungalows in a great setting set into a forested hillside, facing the sea. Think very upmarket centreparcs.
d) Sani Beach Hotel - on the seafront, 3 min walk to the Marina, looks nice, I didn't go in so can't tell you an awful lot But much of a traditional high rise hotel, very large, hundreds of rooms.