So, I like the look of Tullius's armor, but I prefer siding with the Empire. I'm guessing joining the 'cloaks is the only way, but figure I might as well ask.

Nope, helping the Stormcloaks rid themselves of the terrible Failpire is the only way to get Tullius' armor. A fitting reward for a true Son or Daughter of Skyrim!!!

all depends on what system you play on

While you can't Tullius outfit there is a nice substitute for it. In Dragon Bridge, there is a outpost for the Penitus Oclatus agents and they have nice armor. http://www.uesp.net/wiki/File:SR-npc-Penitus_Oculatus_Agent.jpg Of course if you're on the PC then it's a different story.

Completely the opposite. Once again, TES fails us with backwards rewards.
As an Imperial, I wanted nice imperial armor. If I'm roleplaying an imperial, I basically have to KILL some of my own people in order to dress like them properly.

I dunno about you, but I can craft it at the forges. Plus you get a set pretty early in the quest line.

General Tullius armor is one of a kind that isn't found everywhere else. It's just like Jarl robes I was also quite baffled that I cannot get a special armor for my rank, not even the helm that Legates wear (it's called imeprial officer helm and it's sometimes found in chests as loot)

The Penitus Oculatus armor is a darker version of the standard light armor worn by imperial soldiers, although it has a small cape attached to it.

There's also a rare Corinthian style imperial helmet which isn't part of any armor. The only places in which I found it were Brinewater Grotto and in the Temple of Meridia. It looks as if it's part of some kind of cerimonial armor, since it's very polished.

Tullius' is the closest to Maximus type of armor in Gladiator (as far as the muscle etching goes.. Maximus' is way cooler in black). And this game doesn't have anything like that. Kind of a shame actually. Armor like that would look pretty badass with the standard Iron Helmet actually.

Well I was going off the general Imperial armor quote I quoted.
You can get Jarl's clothing if you side with the Empire.
You can get the Imperial Officer Helm at the start of the game if you side with the Stormcloaks (and thus have to kill the Imperials)

About which Jarl clothes are you talking about? Ulfric clothes are different from the rest (and uglier, if I may add)

Join the Dark Brotherhood and get paid to murder for your spoils. Last pickpocketing perk might work.

can you not pick-pocket his armor with the perk?

Ji Soo beat me to it >< would be an interesting test.

Ah, the emperor clothes. Another one of a kind...

At any rate it's a real shame that half of the apparel seen on NPCs cannot be looted.

General Tullius armor reminds me of Shivering Isles... If you liked seducers/golden saint armor you HAD to join the opposite side to get one copy at the end of the main quest. Brillant, just brillant!

There's always the console.

I found it didn't look as good as expected, since the build is made to make you look like a wimpy old man.

Idgrod Ravencrone's robes are different too - you can get them with the console though.... And Elisif's as well.... Tullius's armor looks silly on fem toons, probably for the reason you give!

I recall in Morrowind I wanted to dress like an Imperial guard, but they all had this purple skirt that you could not find anywhere in the game. I had to kill an guard or officer to get it. What I would end up doing is poke a Daedra in the nose and let him chase me to a fort. Since the guards didn't have magical weapons and at the time a magical weapon was needed to kill a Daedra the offended Daedra would wipe out the fort, then I'd kill it, then I'd loot the bodies to get my skirt.

Wouldn't it have been a whole lot easier if they would have just sold me they skirt somewhere?

Anyway, as with all TES games if you want something the game designers didn't want you to have then you have to have the PC version (or be really creative).