Although it may be convenient to land somewhere other then an airport/airstrip it may not always be the smartest/safest thing to do...
Like you mentioned the beach. I guess it would depend on the aircraft, and if you had an aquatic plane and we're going to land on the water that could make sense. Since you said the actual beach, that makes me think your talking about landing on the sand.
Landing on a terrain like sand will likely cause your tires to sink to right in. This isn't all that bad for landing, but when you are ready to leave it could make getting enough speed for take off really difficult.
Also, you mentioned you would do it when no kids/people were around. That is good, but it doesn't mean that kids were not there earlier in the day or the day before. If some kids dug a big two foot hole, and then you came down for a landing and your nose wheel happened to fall into a hole like that, it could probably ruin your day.
Assuming none of that happened, and you nailed a perfect landing you would still have to worry about your propeller. Unless you landed right at the waters edge where the sand is always wet (which is never flat so you'd have to land on an incline), your propeller would start a massive sand storm which throw sand particles into your air filter and all of your vents...
I'd say the beach just isn't a good idea