No family experiences (we're a dive group) but I did win $400 at the Hilton casino...
We did go shopping downtown one day, crowded but entertaining. Fun outdoor market about a block from those brightly colored stores you see on the website.
Ribs Factory in Salinja was excellent if you stay in the resort areas nearby - they have a website.
If some in your group would like a nice beach while you dive, there are several that offer both with on-site facilites: One of the better ones is Porto Mari but Playa Lagun, Varsenbaai and the Tugboat are also options,
Porto Mari is a double reef, get tanks from the snack/dive shop there and it's also a somewhat busy locals/tourist beach. Lagun often has turtles inside the cove in about 20' or less, snorkelers can find stuff in the rocks on either side. Varsenbaai has several good dives at 80', seahorses at 40' near the mooring, turtles in the seagrass at 8' south of the beach and twice we saw about 100 squid under the dock. The operator said the turtles are always there.
One other mixed use site
might be the old Sunset Waters location. It was demolished but had a small, kid friendly cove/breakwater leading out to the dive. And a lot of nice beach. Not sure if you can even get in there now. Bring everything you need.
The Tugboat is one of Curacao's signature dives, it's in 20' so snorkeling is possible. If there's no ship tied up at the pier it's both a good snorkel and a great dive.The best part of the dive is around the point to the south in 60-80' - there's a wall teeming with eels and other stuff. Not the best beach (there's pilings out in the water) but there's a dive school onsite and your friends can get ice cream and cold beer while waiting.