Bargoed is in Minffordd. That's about a mile inland from Porthmadog. It's an end-terrace. It sleeps six, with three bedrooms and two bathrooms, which is handy. The rating is 4 Star. It's comfortable and well-equipped, not just the basics.
You can bring up to two dogs. The garden is enclosed, which helps with that. There's a patio area too. Inside, it's open plan downstairs, with a wood burning stove for cooler evenings. All the bedding and towels are included, and the wifi works fine.
The local pub is about a mile's walk. Porthmadog is five minutes in the car. It's a proper harbour town with shops and places to eat. The steam railways start from there. The Ffestiniog Railway and the Welsh Highland Railway. If you like trains, you're sorted. They go right into Snowdonia.
The closest big beach is Black Rock Sands. It's about three miles away. It's a big, wide beach with dunes. You can drive onto part of it. Portmeirion is ten minutes down the road. It's a strange and colourful place to spend an afternoon. Harlech is about twenty minutes south. The castle is massive, and the beach there is good too.
If you go inland instead, towards Blaenau Ffestiniog, there's Zip World and Bounce Below. That's for if you want something more active. It's about a half hour drive.
For walking, you're on the edge of the National Park. The Snowdonia National Park website has route ideas. For the history around here, Wales Guidebook Castles is a good reference. The area's full of them.
Facilities are all as listed. There's a washing machine, parking, and the usual kitchen things. The local area has fishing and horse riding if you arrange it.