I want to do a side trip to Korat (Nakhon Ratchasima) or Buriram from Pats.

What is the best way to go to Korat or Buriram?

Does anyone know taxi or (mini) bus service?

Personally ,I would arrange a mini- bus to BKK ,then train to Nakhon Ratschima ,enjoy the countryside and views and inexpensive costs 

I am a train enthusiast 

There is a VIP bus leaving from third road every couple of hours , did it once a couple of years ago , good seats , stop somewhere half way and only 3 seats side by side , in a mini bus they can prop as much people as they like .

Si Mongkol Transport Thailand buses & guides | BusOnlineTicket.co.th

Frank

You’d have to transit through BKK. I took a bus from Mo Chit bus station to Buriram not too long ago. It was one of those big double decker buses. Bring a sweater because they love to crank the A/C. 
I’d highly recommend against taking a mini bus. They pack you in like sardines and there’s barely any room for cargo; sometimes they put bags on seats.

If money is no issue you can take a taxi but it’ll run you about 5k baht.

10 hours ago, veill1 said:

There is a VIP bus leaving from third road every couple of hours , did it once a couple of years ago , good seats , stop somewhere half way and only 3 seats side by side , in a mini bus they can prop as much people as they like .

Si Mongkol Transport Thailand buses & guides | BusOnlineTicket.co.th

Frank

Good Advice 

Thank you