How long ago was it that you used Tri-X in 35mm? I recall in 80s when I used Tri-X, there was a quite visible level of grain. But, when I use it today, and I do it regularly, I don't find the grain objectionable even when I enlarge it to 11x14 with small amount of cropping. If you must stick with ISO 400, I find Tmax 400 to be as grainless as it can get for ISO 400 film.
But, if it was quite a while ago you used Tri-X, I recommend you'd try again because the formulation has changed. It's quite nice.