How many times have you listened to the Anthem? How many times do you think you've heard the "standard" rendition? I love Ray Charles. He's one of my all time favorites. But his rendition of the Anthem is about as far away from "standard" as you can get. But, I loved Ray's version.
Just sing, don't do all the inflection and fancy shit, just sing it. Its been so long since someone has done it right I can't even give you a decent example because I don't remember one.
That's because I don't think there is a definition/version of singing it straight. I think each artist puts their own "twist" to the lyrics.
I actually prefer Kiss' instrumental version. I think Shane would too......its actually close to what he would call "straight" KISS National Anthem and Rock and Roll All Nite 2016 Tucson July 4 - YouTube