The Mae Rim Valley is beautiful and is worth a day trip.
In February, we hired a driver he drove us around the Valley. We went to the elephant farm, orchid nursery, the botanical garden, and a couple of hill tribe villages.
We ended the day with dinner at the Four Seasons. Reserve a table on the terrace overlooking the valley at around 6:00pm and you'll enjoy dinner with a beautiful sunset. The prices at the Four Seasons weren't outrageous; our bill came to US$50 for three people, two courses per person.