Rocky Mountain National Park is a showpiece for the Colorado Rockies. It is probably the best first place to visit to see the Colorado rockies. It is also a wonderful place to see Elk in the fall when they are rutting.
These days you have to park your car and ride a bus up to Bear Lake, one of the nicest places in the park. This is a great jumping off place for hiking into the backcountry. Us Americans feel funny about leaving our cars. But, trust me, leaving your car behind and riding the bus is far easier, far more pleasant and an all-around better experience.