If you decide to vsit Nan as daytrip from Bangkok - wich is possible with air Asia and Nok Air - travel light and leave your ag behind in Bangkok. Air Asia offers free bikes at the airport. The best way to explore the city and the major temples in one day and get back to the airport in time. The airport is very centraly located - just some 1,5km out of new town and maybe 3-4 kilometers to the most important historic tempel I mentioned above. Maps are available at the airport information and english speaking help is available at the Air Asia information desk inside the departures hall. The free bycicles are located outside the arrrivals hall on the left.