I'd agree with the Gower and Portmerion Village, a bit further north the area around St Davids is a bit less touristy than the Gower with some good cliff walks. Tenby is ok, Solva is a pretty little village near St Davids.
The Lleyn Peninsula in the North is nice if you like walking, there are plenty of castles around there (Caernarfon and Beaumaris in Anglesey spring to mind). Abersoch is a good place to stay around there, out of season. Llandudno is an old fashioned resort with a prom, pier etc that also makes a good base up there.
Snowdonia is worth a visit, Cadair Idris is a good walk if you are fit and Aberdovey is a nice place to stay. Bit quiet at the moment though!
I'd be wary of the weather this time of year though, it has been raining a lot here recently
If you need any hotel/restaurant recommendations, let me know.