If you ask me what the “most traditional” outfit to wear to Mass would be, I’d say it would be a tunic, robe and sandals… you can’t get any more traditional than what Christ and the Apostles themselves wore
I also, personally, believe the “dress as you would for the Pope or the POTUS” standard, while well-meaning, is a bit unrealistic because for most people, an audience with the Pope would be a once in a lifetime event, but you attend Mass every week or even every day.
If you get hung up on dressing as if to impress an earthly dignitary, that could get pretty expensive, and can also be taken to extremes. Case in point, a certain couple in Chicago with a boatload of VERY pricey handmade suits, ties, dresses and other stuff they probably will no longer be needing soon

(If you don’t know what I’m talking about, google this phrase: “Imelda Marcos of Illinois”)
Seriously, however, I’d say anything that would be OK to wear to work in a professional office or to a nice restaurant would be fine. The main thing is to look respectful, dress in a manner befitting your state of life (no need to look like either a hotshot or a bum) and not stand out in a way that would be distracting to others. I wouldn’t get too hung up on being “traditional”.
On another topic – war stories – my father, who passed away last year, was like odile53’s in that he would talk pretty freely about funny or ordinary stuff that happened while he was overseas (he was in General Patton’s army in Europe, and he landed in Normandy, not on D-Day itself but I think a couple of days later). However he never talked about any of the serious stuff, like people he saw die or whom he may have killed. He had two Bronze Stars but never, ever wanted to tell anyone, not even my mom, what exactly he did to earn them. So his stories also went to the grave with him.