At the major league level I think you can focus on specialists, and usually you will find that stratification already within the hiring pool. So, for instance, third base coaches tend to have higher base running IQs, first base coaches usually are have higher hitting IQs and discipline ratings. When I look to hire the hitting trio (hitting, 1B and 3B), I try to get one who excels in at least one area so that they complement one another, with patience being a constant for me if possible.
At the minor league levels I look for a bench coach who can supplement my hitting and pitching coaches' weaknesses, typically either base running or discipline, though sometimes I get a bench coach with better pitching IQ rating than my pitching coach, and then basically treat my pitching coach like a ML bullpen coach.
I have no idea whether any of this matters though. I think it does, but for the most part I feel kind of like I am throwing darts blindfolded. The only measurable difference I have noticed so far is with Fielding coaches.