Just up the road from me.Lovely place, loads of nice beaches around there.
I'd also drop into Portmeirion,and into Porthmadog itself for a train trip and an ice cream. Good little old fashioned crazy golf in the park. Maybe take a trip to Bardsey Island (Ynys Enlli)
Abersoch is flashy but nice-shops and restaurants.
There is a lovely pub on the next beach along, called Morfa Nefyn.
Just up the road you have Nant Gwrtheyrn in Llithfaen, which is a residentail language centre in an old abandoned village. Go down to the visitor centre (drive is amazing) and go to the beach-you'll have it all to yourself.
Trip to Caernarfon maybe to see the castle and have a fish & chip supper in the Floating Restaurant on the dock.Good indoor play centre there in an old church if you need something for a rainy day.