After 3 nights in Bangkok (not enough but the best we can do), we have 5 nights in northern Thailand, flying into Chiang Mai.
Five days in Chiang Mai seems a bit much to me so I am trying to figure out where else to go before our two oldest kids need to fly back to Bangkok & my husband, daughter & I fly to Luang Prabang. My husband vetoed the idea of Fern Resort (which I think looked great - aside from the drive) and the Pai area as he does not want to drive all of those curves. To give you an idea of our plans this is what I have figured out so far:

12/16 - fly in, have lunch, tour around Chiang Mai & visit Sunday market
12/17 - Cooking class for my husband, son & his fiance at the Chiang Mai Thai Cooking School / bike tour for me & my daughter
12/18 - Elephant Nature Park.

Given my husband's preference to not drive the Mae Hong Son loop, I would like to head up to Chiang Dao, see the caves & do some hiking on the way to Chiang Rai. Should we rent a car for several days? If not, how do we get to Chiang Dao? Do we even have time to go to Chiang Rai?

12/19 - Chiang Dao caves & overnight ???
12/20 - Chiang Rai
12/21 - fly out from Chiang Mai 10:00 am flight

(As I write this, it doesn't look like it's going to work. We will need to stay in Chiang Mai the night before the flight to get the kids to the airport on time. I know this itinerary is too tight.)

One question I have is when we visit the Elephant Nature Park, would we have enough time to visit other sites on the Mae Sa Valley loop or is the Nature Park an all day affair in and of itself?

I am not sure about the timing of things. Should we stay overnight one night around Chiang Dao and leave the next day for one night in Chiang Rai? Should we try to catch a boat from Tha Ton (is that anywhere near Chiang Dao?) to Chiang Rai? Is it worth going to Chiang Dao for just one night & then back to Chiang Mai? I would like to head up to the Golden Triangle as I think my kids would be really fascinated by it all.

As you all can tell, I am confused & need help refining this part of our trip before making hotel reservations. I have gotten so many great suggestions thus far, I am hoping for fresh eyes to tell me what to leave out & what to include. I don't want to drive my family nuts with going hither & yon as they are all very laid back and would most appreciate a very good hike or two and lots of good food.