I've been spoiled by staying at the 5 Star Conrad in Bangkok every time I visit Thailand
You are not going to find this sort of quality in Udon. I think The President is the only place that is going to come remotely close.
I believe that The Sofitel in Kohn Kaen has a good reputation, not that I have ever stayed there - bit out of my budget.
Might be worth your while splitting your time between the two if you are after quality.
President is a bit out of the centre in Udon, I think Sofitel is right in the middle of Kohn Kaen.
p.s. LA's suggestion of bringing your own company with you from BKK is, undoubtedly, a good one...
