Above Wat Phra That Doi Suthep, the grounds of the royal family's winter palace are open to the public (when the royals aren't visiting). Thanks to the mountain's cool climate, the royal gardeners are able to raise 'exotic' species such as roses, attracting lots of Thai sightseers. More interesting is the reservoir in the grounds, brought to life by fountains that dance to the king's own musical compositions.
You can rent a 'trolley car' (golf cart) to explore for 400B.