If I did it again I'd do it the way you're doing it, we were tied to one spot so Rocky National Park was over two hours away, would have spent a night or two there if I wasn't booked in Denver the whole time. Boulder's a cool town, went to Colorado Springs, Pike's Peak and Red Rock. Also caught a ball game at Coors Field. Beautiful Park with plenty of leg room. Get the Express option for the highway, makes travel much quicker, worth every penny.