well, maybe its not the most impressive set of teams to make the sweet 16 in a single region of all time... but its by far the best i've seen, and it is so awesome i figured i would post it.
i think you have to take into account not just the success of the coaches, but the success of the coaches at that level - which is what makes our region so magical. but general success is definitely there too - with over 40 titles as a group, and 7 minimum each... well, the general success is definitely there :) anyway, here are the 4 teams:
1 seed - post emy/dcy - with a handful of d2 titles, dcy in d2 tark also boasts (i believe) the most wins by any coach in a single division, ever.
2 seed - concordia girt/daalter - probably the most successful coach in the new engine era. but in d2, its not even close. he left one of his schools so i am not positive, but i believe daalter has won 3 titles at two different d2 schools just in the new engine!
5 seed - glenville coach_billyg/gillispie - i coach SIUE in d2 tark, where 9 titles, a best-ever 7 straight final fours, and a best-ever 14 straight elite 8s define one of the great dynasties in HD history.
6 seed - n kentucky fussyd - i forget where, but fussy rattled off a good 4 or 5 titles in no time flat at his d2 dynasty not too long ago (before the new engine, but since the new worlds came out). also, his run was with the zone defense - which, to the best of my knowledge, makes his d2 run the best run ever with a zone defense.
considering these are the 4 coaches making up the sweet 16 of a d2 region, not even a final 4, i figured this was roughly as good as it gets! which ever team manages to survive to the final four sure has earned it =)