These days, solitude is found in my bedroom. I just shut the door, turn off the phone and I am not bothered. I like being alone, maybe a lot more than I should.
Back in the day, when I had kids, it would be the bathroom. Even then, I usually got bothered.
The best scenario for me would be a small cottage on the banks of the ocean. Somewhere private. No people, no phones, no distractions. Just the relaxing sounds of the waves.