Glanrafon Isaf is a converted barn near Caernarfon. It sleeps twelve, in six bedrooms across the main house and an annexe next to it. There are four bathrooms. It's got a 4 Star rating.
The main room is open plan, kitchen dining and living all together. It's good for a big group. The river runs right past the bottom of the garden. You can fish there, or just walk along the bank.
Outside there's a big deck with a barbecue. The garden is yours to use.
Inside, there's a wood burning stove, WiFi, and a TV. It has a washing machine, dishwasher, and the bed linen and towels are included. You can bring one dog. There's parking on site.
Caernarfon is a few minutes away by car. The castle is the main thing to see. The Welsh Highland Railway steam train goes from there up to Beddgelert, which is a nice trip.
You're about twenty minutes from the Menai Strait to get onto Anglesey. The coast there is all beaches and little bays. The mountain is in the other direction. You can drive to Llanberis for the Snowdon Mountain Railway if you don't want to walk up.
Llandudno, Betws-y-Coed, and all the Snowdonia spots are within a half hour drive. Useful links for planning: Snowdonia National Park and Visit Wales.