Not all landscape designs need to revolve around plants and formal gardens. You can add some playful elements to the landscape to satisfy the kids or the young at heart. The following are a few ideas to consider.
Idea #1: Splash pad
A splash pad is an excellent way to add some water play without installing a full pool. Another benefit is that splash pads don't require the maintenance and water treatment that a pool requires. You can go simple with a pad that features a few fountains and jets or make the pad more ornate with water arches and dumping buckets. You can even keep it grown-up looking by having the above-ground features designed to look like statures or arbors. When the pad isn't in use for water play, it can double as an extra patio area.
Idea #2: Lawn chess (or checkers)
The most common way to do this is to create a checkerboard lawn using grass and paving stones for the alternating colors. You can go large and create a life-size board that uses extra-large playing pieces or even people. Another option is to create a smaller board that uses frisbee-sized playing pieces. The limit depends on your desire and space constraints.
Idea #3: Lawn bowling
Create your own bowling alley right in your backyard. It's as simple as installing a wood deck the width and length of your desired alley, and then sanding it smooth and sealing it against weather. If the kids ever tire of bowling, the deck will serve double duty as a place to set a bench and a few potted plants so you can sit out to enjoy your yard.
Idea #4: Truck station
This idea works great if your kids want a sandbox but you are afraid a sandbox would become a litterbox for the neighborhood cats. Instead, landscape a garden bed with plenty of hills and valleys. Then, install road tunnels through some of the hills with a PVC or drain pipe. Map out the road and then use concrete or asphalt to lay it down. You can even create it out of pavers. Paint the lines on the road and then add kid-friendly landscaping to finish it off. For example, steppable groundcovers, like creeping thyme, along with soft wood mulch works well. Your kids will have a place to push their trucks around, and you will have a beautifully landscaped garden bed.
Talk to a landscaper or go to sites of landscaping companies in your area for more creative and playful ideas.