I have a standard "playbook" I use. About 4-6 combats(or dangerous traps or obstacles) between short rests, each one set up to make one of the PC's shine and maybe another less effective. The traps or obstacles will be set up to sometimes make a PC make a skill check or saving throw they might be bad at, like a pressure plate set up with a weight limit that the Halfling rogue wont trip but the goliath would, something along those lines. For the social aspect, same thing. Sometimes the Fighter is always in the tavern, so the CHR check goes to him as the most "well known" of the group, with the idea that if he fails and gets into trouble then the Bard can talk him out of it but if the fighter succeeds the group will get a bonus to later checks ("Hey the friend of Tordek the mighty, any friend of his is ok by me.")
Since I am choosing who will make a checks to make different players shine at different moments, I will change the DC of things no matter what the published material says. I understand the concept of a party face, but unless a PC plays a shut-in he will have to interact with someone in the game world sometime. The optimized archer fighter build will sometimes have to fight hand to hand, the wizard will have to fight in silenced room, etc.
The idea is to sometimes get the players out of their comfort zone, that's what makes in fun.
So the fighter who put 16 CHR on the sheet will be rewarded, I will work it in somehow. The fighter who plays it brave but suboptimal, maybe by charging through a door that the rogue hasn't checked for traps yet wont get punished every time for it. That PC is trying something different, just trying to have fun instead of "winning," that should be encouraged.