The Bali cottage was a great experience. We stayed here for three nights after a few nights in downtown Kailua kona, so I was ready for something more relaxing, outdoorsy, and home like. Having our own fully outfitted kitchen was a joy and there is plenty of indoor or outdoor spots to sit and relax. I think the things I likes the most were the very comfy bed and the lush, cool landscaping. The kona side is hot at sea level during the day, but in the shady cool Bali garden it feels just right.
The hosts were great too: welcoming and informative but not intrusive at all. They have snorkeling gear, in case you forget yours.
The area is really nice too. For sunbathing or taking a dip manini beach is nice and kid friendly. For a bit more adventure I recommend renting a kayak and going to the captain crook monument. 30 minutes of paddling each way and very good water visibility and reef. We saw dolphins and a manta ray! For a more secluded beach take a 15 minute walk to Ke'ei beach (and go back in time 15+ years). We also ran to city of refuge (Hinayana) and back, 8+ miles, but get an early start for that, it's a HOT road.
I guess the only thing to warn about is that if you want to take a 20 minute hot shower you'll probably drain the tank. But come on, you in Hawaii, just rinse the salt off and relax!