The Cabin Cefn Mawr is in Cefn Mawr, near Newtown. It's a detached lodge. You're on your own up here, set back off the lane. The view from the deck is over fields and hills. It's quiet.
It sleeps four. Two bedrooms, one shower room. It's got a 4 Star rating. It's modern inside, new feeling. The log burner works well. The deck is good for sitting out if the weather plays ball. There's a lawn too.
The stairs to the main bedroom are a ships ladder style. They're fine if you're steady on your feet, but maybe not for very young kids or if you have mobility issues. It's just how it's built.
Newtown is about ten minutes by car. There are supermarkets, a cinema, and the usual town things there. For walking, the Glyndŵr's Way passes nearby. The Cambrian Mountains and the Mid Wales region are right on the doorstep. You can drive up to Lake Vyrnwy in about half an hour.
If you want a day out, the coast at Aberystwyth or Borth is just under an hour's drive. The National Trust Powys page has details on local places like Powis Castle.
Facilities wise: it's got parking, WiFi, a TV, and the log burner. Bedding and towels are included. There's a cot and highchair. You can bring up to two dogs. There's a BBQ.