Formal attire outside in the heat or in the action wouldn't really make sense, but perhaps in guarded and conditioned command rooms, as some general formal attire?
For example, in F2, there were also many bluesuits on the Oil Rig, but i guess they were moreover soldier fatiques than vaultsuits, but that's only IMHO.
Distinguish marks are a great idea, one could just edit the texture to add some slight alterations to the different squads - the patrol or base defence for example, as well, as command staff.
One could lack helmet or wear a hat with PA in the Navarro, though - for example in the officer casino.
"The sergeant with white markings positioned himself right next to SPOILER's platoon, making sure she stood right next to him. The entire base had been mobilized, all except those on guard duty and those sleeping. There must have been at least a thousand people, some in power armor, some in combat armor, but most in the same uniform she wore. Dornan stood on the other end of the line, flanking her platoon.
In the center of the courtyard stood a man in power armor, but on his suit, every plate was gold-trimmed, and two gold-colored ropes hung from his shoulder, passing under his right arm. An odd steel construction stood next to him, flanked by two troopers in power armor, with black shoulder plates. A third man in black-shouldered armor and lieutenant's chevrons marched to the gold-plated one, saluted, and stood rigidly in front of the construction."
"EC Company", the sergeant explained as he walked with her back to the elevator topside, "short for Enclave Control, is basically the Enclave's first line of defense, securing the borders of Enclave territory and engaging threats. Right now you're in I-sec, Internal Security, which is where all newbies start out." He pointed at the blue triangle on the bicep of her uniform. "Affectionally called 'the Blue Balls.' I-Sec is the comfy, boring trash can of this force. EC are the guys who do the real work. Most privates take years to transfer from I-sec to EC, but in some cases a speed procedure can be worked out."
SPOILER nodded, trying to keep up with the sergeant's brisk pace.
"This force consists of three major divisions. I-sec and EC are two of them. Then there's EncStorm. Enclave Storm Division. Think of them as the Enclave's big, brutal, stupid sledgehammer. They get sent in for all situations that have only two steps. Step one, shoot. Step two, sift through the ashes."
"So they're probably the ones who…"
"Raided your SPOILER, yes, probably under the command of Secret Service. They go well together. On one side, you have an army of psychotic, brainwashed maniacs, and on the other, you have a secret branch that loves atrocities. One has no brain, the other has no heart. A match made in heaven," the cynicism in his voice was unmistakable, speaker distortion or not.
"Which color are they?"
"I-sec, blue. EC, white. EncStorm, red." He sighed. "Red, white and blue. Like the star-spangled fucking banner."
SPOILER had no idea what he'd just said. "So I'll need to change the markings on my uniform then?"
"You'll get a whole new one." He stopped walking and looked at her. "But you won't be wearing it very often."
SPOILER. "How so?"
"It's mandatory at all times on duty, except on formal occasions, for all EC members to wear Mark II Advanced Enclave Power Armor."