Weather in April can be like a UK summer - changeable. May is better, also everything has opened up by then.
If you want a resort that is not too touristy - look at Turunc, Akyaka or Dalyan.
Although these resorts are all quite small, (Dalyan is the largest), they all have plenty of bars and restaurants, and trips out including some excellent boat trips.
The scenery in all these places is spectacular, you'll find them lovely places to spend your Anniversary. You can have a wonderful, relaxing holiday but still with plenty to keep you occupied when you want it.
Aegean Flights are selling flights now, they were very reasonable when they first came out, but must admit haven't looked lately.