One of our go-to Saturday destinations when we don't have actual "plans" is walking along the river by REI in downtown Denver. We have found sometimes the best fun is had when we just take it easy and enjoy the stroll rather than trying to plan out an event or destination for the day, and this makes for a fun day for a variety of reasons. First, we swing by REI and pick up our favorite shaved ice cones from local awesome shave ice maker Callie, who runs Summer Snow Shave Ice which happens to be the most amazing, delicious, refreshing and adorable teeny tiny booth in front of REI on weekends in the summer (usually there 12-5 on saturdays and sundays from mid-may to September). She runs her booth out of an old ski-lift gondola she pulled down off the mountain. Not only is her shave ice amazing, she's the friendliest, funniest shave ice maker in Colorado. You don't want to miss this step, I promise. Get the vanilla- it's amazing and completely nuanced in only the way vanilla can be. Bonus, her flavors are made from fresh all natural ingredients combined with 100% Real Fruit.
Next, we either walk or ride our bikes along the platte river. In the summer, the river comes to life with people paddle boating, rafting, swimming, splashing, chasing their dogs, and general joy inducing chaotic play that only Colorado can produce. Our daughter loves to wade in the shallow water and feed the ducks that sometimes congregate around the platform overhanging on the REI side of the river. If you cross the river, you enter a beautiful open park that is our go-to for biking trails, slack-lining with our fantastic Gibbons slackline kit (that we bought right there at REI of course), or hanging out in a hammock and enjoying a breeze.
Inside REI on bad weather days there is a playground on the top floor (complete with a slide and a tunnel) and a rock climbing wall as well as a beautiful starbucks that is probably worth it's own post in the world I exist as caffeine credits are generally the highest value after wine :) In the winter, we will sometimes head to REI and grab coffees, drag ourselves upstairs with some magazines or books, and park in the kids section on a bench while our kiddo plays on the slide and burns off energy in only the way a child can. The atmosphere and playground beat the heck out of those at the bigger malls, and we always find something amazing (like our aforementioned hammock or slack line set) to take home for when the weather isn't so crappy.
If the weather is nicer, the outside of the store features this nice rock which kids just love climbing on. Technically you aren't supposed to let them of course, but it's pretty much a local attraction in itself. I remember very well the first time Taylor made it to the top- she was shocked to have made it so far. There are also these fun statues of bears which she always wants to sit on before we leave.