Shinagawa Beach in Balapitiya on the south coast of Sri Lanka is just such a beach. Being the only hotel on this stretch of beach you are pretty much guaranteed to have it all to yourself (except the occasional local wandering past of course).
All room categories have uninterrupted sea views so you can lay in bed and watch the ocean or sit on the balcony taking selfies at sunset. Facilities include a spa, small pool, a restaurant and fully stocked bar - don't forget to try their Sri Lankan curry!
If you want to head out for the day, then flag down a tuk tuk or ask reception to order your a taxi and either go shopping in the nearby town of Ambalangoda. Alternatively book a speed boat ride up the Madhu River which departs from their sister property, The River House.