If I want just a slight bit of an ester profile, I use Wyeast 1450, WLP51, or Pacman. And for an extra hop to play well with Ultra, I would recommend Crystal.
For a touch of esters, I like WY1272 or 1332, I find them to accentuate the sweetness of the malt a bit as well, which will make it seem a little less bitter. 1272 is my favorite for brown porters and other malt forward ales. 1968 works pretty well as well, and it also leaves some sweetness.
I think Columbus would make a decent match with ultra. You could also go with Mount Hood, Liberty or US/German Hallertau.