Should we book before we arrive or when we are in Chiang Mai? Visiting December 2018
Also please recommendations to the best sanctuary's in Chiang Mai.
I would also book now as have been reading so many stories of people missing out. We also booked many months in advance. :)
Aside from ENP, which in high season can be booked-out for many weeks, you can arrange most other day tours last minute (day before) with your hotel/guesthouse or travel agents. And note there are many (many) other elephant parks within 1-2 hours from CM.