Amarr

Of the assaults suits...

...don't go Caldari . The racial bonus is bad and shield tanking is lacking a bit, and... well, things may improve with 1.8, but I wouldn't bet on it. The suit is effectively being nerfed in my opinion, as it is losing two rather nice shield based bonuses in exchange for a lackluster reload bonus and a decent weapon/sidearm fittings bonus. Hold off on this one.

The Amarr suit would compliment whatever you have in armour skills, and the bonus is great (once you get to at least lvl 3). However, the bonus only works well with the standard-variation of the Scrambler rifle and the Laser Rifle, and those weapons are not exactly for everyone. They are very aim-intensive, so be real with yourself: Is your aim good? If not, the Amarr may not be the assault suit for you.

Personally, I'd go for a different role, like the Gallente Commando you mentioned. The commando has some fun builds, like the AR/Shotgun combo, and the plasma cannon can be a fun weapon on rare occasions on the commando as well. It would also open some doors. You get a basic heavy with it(with an easy path to Sentinel), which may be of use in certain maps, and would be great as a platform for the eventual Gallente heavy weapon (plasma mortar, if rumors are to be trusted).

Anyway, just a little reminder that regardless of what you choose to do, there is no need to go all in (such as getting Gallente Commando lvl 3 in one SP spending session).