Things I get into Power Armour for:
1. Getting it back to Sanctuary for my Iron Man style Silo of suits. And even then... I usually just make my companion get in it so I don't have to wear it.
Things I don't use Power Armour for:
Glowing Sea... really, my normal gear and a Rad-X pretty much nixes any worries I might have there. But it's far more amusing watching my fiance play through there. He's specced deep into the Endurance tree. He just goes in the daytime and his rads actually go down while he's there. After he tangles with a few deathclaws, he goes and stands in the super rad water for a second or so to heal, then just goes wandering around like normal so the sunlight can remove all his rads.
Like others have said, outside of the Brotherhood, I'm not sure why anyone seems to think it's so required in the game.
I hardly ever use it. Since all my armor is deep-pocketed I find that PA actually reduces my allowable carry weight and it doesn't seem like the armor is that much more effective than what I normally have on. And I agree with the people who are saying that a backpack full of Rad-X and Radaway does me just fine.
I thought there was a radiation suit for the glowing sea in the launch trailer, but I never found one.
I got mt first Hazmat suit from a vendor a few hours into the game...i can't remember exactly but it was either Carla or another Wasteland trader.
Well I used the first suit when I got it. Used it again going into the Glowing Sea. Second time into the Glowing Sea I just used RadX and Radaway and was fine. Won't touch it again. I do like it better than I did in prior FO games, but I never used it in those games either.
My first character only used PA but my second doesn't beside the glowing sea. It's not required. I'm just too lazy and cheap to buy a radiation suit when I got PA for free(for my second character).
Sneaking in powerarmor is fun on survival .... *cough cough*
Never touched it, since the beginning.