[SixOfSpades]

When building "perfect" parties, I try to start with what qualities I want, rather than the kinds of people I want. For me, this is what's important:
* As many people as possible have a good chunk of Warrior levels
* As many people as possible can wear Full Plate
* At least 1 person always gaining levels as a Thief
* The Tank must have excellent Saving Throws
* As many people as possible (except the Tank) are spellcasters
* At least 1 person always gaining levels as a Mage (except in BG1)
* Both sides of the Priest scroll (Cleric and Druid) are covered
* As few people as possible restricted to using Slings

After all that, I designed 2 Multiplayer parties--one of them was all Humans (most of them Dual-Classed), the other all demihumans (all of them Multi-Classed). I think I'll sit on my "results" for a little while longer, though.

Rockstar: Why would you make the Fighter->Mage Dual at Level 8? You don't gain anything important at that level. Usually, the best times to Dual are right after you gain a new Weapon Proficiency point, a Saving Throws bonus, a increase to your ApR for being a Warrior, and/or some boost from whatever kit you have. I should also note that most Dual-classes (particularly the low-level ones) have their power defined by how many levels they put into their first class.
Also, your Cleric/Thief will never be able to use Bows, unless you've got some mod that allows Clerics to use pointy weapons. A Thief Dualed to Cleric could do it, though, but only if he waits to Dual until after he's got Use Any Item.

Inquisitors: Dispel Magic is very much based on the relative levels of the casters--in this case, let's say that a Cleric is trying to Dispel some magic that was cast by a Mage. If the Mage and Cleric are the same level, the DM has a 50% chance to succeed. If the Cleric is a higher level than the Mage, then for each level of difference the DM has an extra 5% chance to successfuly Dispel. (And if a person is affected by Dispel Magic, all dispellable enchantments on them are removed simultaneously.) If the Cleric is of a lower level than the Mage, though, then for each level of difference the odds that the DM will succeed diminishes by 10%. That's the way it is in BG2, at least: In BG1, Dispel Magic automatically removes everything, no matter what level you are.
The trick about Inquisitors is that their Dispel Magic does not use their actual EXP level as their caster level: Instead, they cast DM at twice their regular level, so as soon as they hit Level 10 they can throw it at Level 20--which is the cap on casting level for all spells, so they're already at the maximum. This means they've got a pretty good chance to instantly strip away all magical protections from every Mage in the game--and they're utterly helpless against Liches. Why? Becuase no matter what their caster level is, Dispel Magic is still only a Level 3 spell, and Liches are immune to all spells from Levels 1 through 5. So the Inquisitor is way OVERpowered against Mages, but way UNDERpowered against Liches, an imbalance that I intend to rectify.