That is what I used and it worked pretty well for me. Thieves are nice because they are fast and often hit more times than warriors do.

Warrior
Theif
Black Mage
White Mage
is a good team that I used many times but another team I used alot was
Warrior
Monk
Black Mage
White Mage
both teams are good IMO

Worrior
Red Mage
Black Mage
White Mage

This is the team im currently using and its going pretty well. I find what the red mage lacks in mp hit makes up for in attack , if well equiped. The red mage acan pick up all the spells that you cant get with the others...well mostly.

I always thought that red mage was a hard class to use. Simply because while they are awesome at the begining of the game, then end up sucking by the end. That is because their magic only goes to level 2 and their attack ends up being medicore. They are basically a jack of all trades but good at nothing. They fun to make the game more difficult though, but I would not use them the first time I play the game.

Its the same tactic for evey final fantasy game 2 fighters ,2 magicians thats how you have to role play always.

warrior
red mage
black mage
withe mage
thats my team

i've used that several times with good success.

using a thief instead of a red mage is also good.

2 warriors, a white mage, a black mage. Honestly, there isn't much use for thieves or monks later in the game...

there is perfect use for Monk/Master latter in the game... heck there is even use for them at the begining, Unepuipt everything from them and they are the best charecter...