Usually my first set up is one of these depending on my mood:

Bartz- Monk/theif
Galuf- Knight/White Mage
Faris- Blue Mage/Black Mage
Lenna- White Mage/Blue Mage

After the Slash is what I do most commonly... the first one is the one I did one of my first times though.

Basically I pick up white magic abilities for Galuf then Switch him to mystic knight. Therefor I have a tough character who can heal/revive if neccesary.

Bartz I like picking up the theif's swift foot ability but being a monk is fun... and a monk with the thief's abilities is even funner. Plus I like How Bartz looks as a monk.

Faris I generally have as a blue mage although I also use her as a Black mage with Blue abilities... depending on my agenda at the time(whether or not I am trying to learn Blue spells or not.)

Lenna is in much the same boat as Faris. Go white mage with blue spells or blue mage with white spells.

And actually my classes don't change much later on, Bartz my go ninja later and Lenna if I am bored may be samurai or time mage with white ablities.

I find this party to be good and flexible... other then my lack of time magic of course but I generally don't use it or summons even if I have them.(unless I want to warp out of a dungeon but then I can just class change real quick and poof)