Now, I know that the Imperial Guard folks don't really have to have similar fighting styles to the Space Marine companies they support, but I'm trying to build my army nice and fluffy-like.

With that in mind, are there any particular IG regiments you all think would be best suited to work with the Salamanders. I can't decide if you'd want a regiment that compliments them in a yin/yang way, or one that has a fighting style similar to the Sallies.

Krieg seems pretty close to Sallies: tough, resililient, like to use meltas.
Tallarn seems like a good counter point: Quick, hit and run, use rockets/mortars.

Any thoughts/opinions?

The Steel Legion was introduced along with the Salamanders during the Third War for Armageddon. So they have fought along side each other before.

im not heavily familiar with the fluff but the tallarn(sp) dont really seem to me like they would work with the salamanders, im going purely on looks tho lol, bu the steel legion def seems like it would work well, especially given their parts in armagedon

Yeah, Steel Legion is actually what I think I'm going to be going for.

Witt, pig iron makes some gas mask heads that look almost like they could be used for steel legion. Though, thinking about it, they don't look exactly like Steel Iron when coupled with the Cadian bodies, but close enough for government work lol