At the risk of being completely dismissed as a Flynn homer:
I haven't seen nearly the number of Ross courses as you, Jim. But in my experience, I have yet to see an American architect that had a consistently better selection of par 3s on individual courses and throughout his portfolio than Flynn. Maybe the bunkering (multiple on one side below green level and a single on the other side at green level) was systematic on some courses, particularly Rolling Green, but I think he must be considered among the greats at designing a set of par 3s for a course. As for par 4s, Flynn is up there with the very best as well. While not at the very top of the pyramid, Flynn's par 5s are outstanding. One of my favorite par 5s of all is the 3rd at Philadelphia Country Club. Flynn, perhaps due to the Merion influence, at times had only two par 5s on a course, especially some of his championship courses. Rolling Green is an exception with the 18th as a particularly poor par 5 for better players, especially situated at the end of the round. It should be a par 4. I'm sure Mike "Knucklehead" Malone will get on me about that again. The two par 5s at Shinnecock Hills and Huntingdon Valley are excellent. Huntingdon Valley and Shinnecock Hills in particularly are strong in the par 3s and par 4s.
I don't know Tillinghast well enough either, but what I have sampled leads me to believe that length and overtly dictated direction were the most important factors in the strength of his par 5s rather than angles, subtlety and temptation in his designs. I could easily be wrong though.
Colt may have been as good or better at par 3s, though I haven't played enough of his courses to determine.