1. Makena Beach State Park, aka Big Beach
This is the most gorgeous beach I know in Maui and that's saying something, considering how many beautiful beaches there are on that island. It's a very long, very soft, very sandy stretch of beach, and it can get some very big waves (depending on the season and time of day). The water was definitely too rough for my kids when we went there on our last Maui visit, but I hope that one day, when the kids are a little older, I'll be able to enjoy the beach and the waves with them.
DT Fleming Beach Park
Another fantastic beach on Maui: lots of rocks with sea life to explore in the shallows, turtles and fish swimming by if you're snorkelling, nice waves, good sand, and even some shady trees. Just beautiful.
3. Pu'unoa Beach, aka Baby Beach, Maui
The perfect beach in Maui if you're bringing little kids or even babies. Grass and sand to sit on, a reef protecting the shore from big waves, and a fun place to just relax and hang out without worrying too much about your little ones getting tumbled by rough waves.
4. Meia Praia, Algarve, Portugal
Many years ago I lived and worked for a while on the Algarve coast and Meia Praia was my favorite beach. It's a loooooong stretch of sand with beautiful water for swimming, boating, and windsurfing. I really hope to bring my kids there in the future: haven't been there for so long and would love to re-visit that stretch of sand!
5. Playa del Ingles, Gran Canaria, Canary Islands
This beach is very busy and very crowded, especially certain parts of it, and that kind of stuff usually turns me off. But there are some very good reasons why this particular beach is that crowded: it has beautiful sand and great water for swimming and playing in. My kids loved this place and so did I, once I got over the crowds. Just put your beach towel down away from the worst crush of people, or grab some of those rental sun chairs, and enjoy.
Third Beach, Vancouver, Canada
My favorite beach in the Vancouver area (though it's a close call: check out my other local favorites here). Great view of the mountains, lots of ships and boats and planes to look at, and lots of sea-life to explore on the rocks and in the sand. Also, the sand is perfect for playing in, and the water is good for swimming (if a little colder than in Maui!).
Spanish Banks, Vancouver, Canada
Another beautiful Vancouver beach. It's very long, the water is shallow, and there are stunning views of the North Shore peaks (where you can go skiing in the winter) as well as of downtown Vancouver (bring a camera if you're so inclined!). There's also a nice path for riding bikes or going for a walk along the beach if the weather isn't good enough for just sitting around in the sun and sand.
Long Beach, Tofino, Vancouver Island, Canada
This is an absolutely stunning beach. There are lots of hiking trails around it, there's rich ocean life to explore, water sports like kayaking and windsurfing are available, and it's just a wonderful place for beach-combing.
This tiny stretch of sand outside my parents' summer house in Sweden is heaven for me and the kids when we visit in the summer. Tiny fish play around the dock, the kids swim and splash in the water (even when it's not that warm), and the sand is great for digging and rooting around in. To me, this is a little bit of paradise.