Troncones

It depends on when you are coming. I've only seen Mi Casa Su Casa very busy during Christmas and Easter and Mexican Holidays but so is everyone else. Also the main beach has very swimmable sections...I swim out in almost in front of house (a little to the south) every day and so do many people. As anywhere in the ocean be aware of rip tides..and know your limits.
There a plenty of awesome places to stay so check Robs list of rentals and maybe look on some other sights..like tripadvisor. Mi Casa Su Casa could be a great place to start and then explore around while you are here and see what suits you. They do have a nice restaurant looking out to the ocean. To answer the question though..I never stayed there. I've stayed at Hacienda Eden, Inn at Manzanillo, Raqueros, Regalo del Mar and Casa De la Sirena and all were wonderful!