Rangers are awesome in a ranged party, I agree. But If you have two melee fighters, I think it's better to either add another than take a ranger if you are going for melee, or take one melee guy away if you are going for ranged. If you play a melee-heavy party, you'll have to move every turn to keep in range of the enemies, especially later in the game. If you play a range-heavy party, you'll be standing still and shooting, and you only need one tank. If you play a mixed party, you have to either move an get penalties in order for one half of your party to take part in combat, or not move, not get penalties, but have half your party not contributing.
So it's better to pick a focus and stick with it, in my opinion. Although actually, if you are going bard+gadg, a ranged party seems in order. You certainly want to keep the valkyre for the stamina spells.
However Tales, I think I was not clear. It's vital to have a mage-spell capable character (i.e. bishop, mage, or at least the weak samurai) for missile shield. It's silly to go without it unless you know what you are doing. But it's also vital to have a good amount of healing spells (in a six-man party, one of your chars will spend all their time healing unless someone helps out), and a psionic for haste is handy. So basically, of all the spell schools wizardy and divinity are absolutely essential, psionics is useful, alchemy is not vital (of course in terms of offense the usefulness is reversed, with alchemy by far the best and mages not so great).
To put it short, take a bishop instead of the mage and have him get divinity and wizardry. Also consider dumping the fighter and adding another bishop focusing on alchemy and psionics.
