Taxi in Udon?

I used the Limousin/minibus service as mentioned above at Udon airport last week. 80 baht, office straight in front of you at arrivals public area. They will drop you anywhere within reason in Udon city area; maybe even further afield. Doesn't have to be a hotel. You can also arrange a vehicle for other destinations at the office (certainly Nong Khai was advertised). That is why there are no taxis at the airport.