that's pretty much what i did last mar/apr, same trip, though ended up in golden triangle, and then down myanmar border. i bypassed CM, as being there before, and didn't do anything for me either.
travelogues are on this site. loei is always a good 1st stop, whether in town, or couple days in phu rua area, phu rua resort was nice place to relax for 2 nights. i tried to keep it under 3 hrs a day on the road, stopped for one nighters, unless something interesting, or nice guesthouse for R&R. such as the one in playao, very relaxing, though not much there, except gh was across from nice lake. should be much better traveling this time of year, as it was slash and burn time when i went, so long distance visibility of hills behind hills were limited. it's a bit further up the road, but really nice 'hall of opium' museum in chiang saen/golden triangle. wife and son should enjoy that, and eccential for a learning experience, as no the usual thai white wash of history, fairly accurate and not complimentary of thai drug history. though it's pretty much one way up, and back. unless deciding to return via river.
if this is just going to be a xmas break holiday, 2 weeks, then maybe not enough time for golden triangle. chaing rai was a bit of a disappointment for me, though wasn't expecting that much, but much worst than i imagined. if i was to do an out and about, and not been there before, but now know, would head to golden triangle, then return via khiang khong and continue along he river, back via loei again, then up to chiang khan and again along the river back via nong khai, or you could actually head back to nong wa so via sri chiang mai, turn south there or tha bo if not wanting to go via nong khai, as sure you've been there enough.
do you have laptop, and have i given you my mapping software, comes in very handy for self drive.
