We went for a hike in Boulder at the very popular Chatauqua park- this was probably one of the busiest outdoor parks/hiking trails we've been on yet. It was an easy-moderate hike which Little Berry did just fine along side us except for a few spots where the trail was icy.
It was also very popular with dog owners, and since we had our dog Oreo along too there was much tail wagging&sniffing happening during the hike.
Boulder has an off leash dog tag you can purchase if you prove your dog is under voice command, but we always just stick with him on-leash as it seems safer than having to worry about something happening. Less fun for him I'm sure, but I think safety rules.
There was some tree climbing by Mr.T, and sunshine soaking by all of us.