I've never completed the original BG (I was one room from the final battle and bad things happened), so I decided to install BG, BG2 and then apply the BGT patches. This will be a multiplayer game, so I'll make an entire party to go through the game (just hope I don't get tired of flipping between full/windowed for MP).

I do have a few questions for party composition. Here is what I am currently planning:

Ranger/Cleric (half-elf)
Wild Mage (human)
Archer (elf)
Inquisitor (human)
Kensai(13)->Rogue (human)
Kensai(9)->Mage (human)

Since I have never taken a party from beginning to end, I'm wanting to make sure that I'm not missing something important. I'm open to suggestions and comments, especially on the Kensai levels. Also, I was under the impression that a character can dual class into a specialization, assuming their Int is high enough, so I'm planning on going Conjure with the Kensai->Mage.

Other classes that I pondered: Cleric->Necromancer (always liked the concept), Monk, Skald.

You say it will be a multiplayer game. Did you mean you're creating your own game in mutliplayer mode, then planning on playing it single player? If so, there's no need to flip back and forth from windowed mode once you have your party made and you've started the game. Just move that multiplayer save file into the single player save folder and you're good to go.

One of the big draws of BG2 are the companions, and each has their own side quests attached, so I'd recommend leaving one party slot open so you can trade them in and out to get their quests and stories. So, a 5 character party instead of 6.

I'll leave it to others to comment on the party make-up.

This is good to know! Hmm, good point. How many NPCs in BG2 are linked (the 1st 3 groups of NPCs you find in BG1 are 2 chars each).

None that I recall offhand.

I would also recommend having either more multiclass characters and more other races. A hobbit fight/thief or a gnome fighter/mage or a dwarf fighter/cleric. It just makes things more interesting. Or try some of the specialty classes.

Powergaming can be fun, but it can also get old as all the baddies die too easily.

Hmm, not really going for power gaming, but I can see what you mean on mixing up the races a bit. Basically, I made a list of roles that I wanted to fill, then looked at what all was available

I could mix this up with a Cleric/Mage (heals and spells), Fighter/Thief (dual hammers), Fighter/Mage (archer/spells), Inquisitor or Undead Hunter (2H full plate), Wild Mage (RNG factor), and either a Monk or Skald, but TBH, this seems like it would be more powerful than the above listing.

The kensais will be extremely painful in BG1. They can't used ranged weapons and their AC is too pathetic to last in melee, even your wild mage might contribute more to physical combat.
Playing the whole BG1 and a big part of BG2 without a thief won't be fun either.

I'd replace the kensai13/thief with a fighter/thief multiclass and the kensai9/mage with a sorcerer, even at the end of BG2 they'll still be more powerful than the dualclasses.

Good points on the Kensai. I've decided to swap things around a bit:

Cleric/Mage (thought about Cleric->Necro, but decided on multi)
Fighter/Thief (this will be my dual wielder, axes)
Fighter->Cleric (hammer and shield)
Inquisitor (2Her)
Archer (solid ranged)

Not sure on my last class. Either Skald or Wild Mage, as both will be ranged. I'll probably go Skald, since a buddy of mine actually wants to do a multiplayer game and a Wild Mage could be entertaining for that. :)

A few thoughts:

A Gnome Cleric/illusionist gets and extra spell slot per level, but at the cost of not being able to cast necromancy spells. If your PC is a mage you can probably make do without necromancy spells on this character (also, some cleric spells as similar to the spells you miss out on)

Thieves can only backstab with melee weapons usable by pure class thieves. This is to say: Daggers, short swords, long swords, scimitars, katanas, clubs, and quarterstaffs. When picking classes, it is worth noting that half-orcs can have 19 STR and CON, but that halflings get a boatload of extra thieving skills which are pretty handy starting out.

If the options are Skald or Wild Mage, I'm going mage. Your Cleric/Mage will make a nice secondary caster and allows for some interesting spell combinations, but you should probably have a primary mage.

In a party of 6 specialized characters are better than jack-of-all-trades. You want them to excel in their domain, your cleric/mage multiclass will neither be a really good cleric nor really good mage so if you don't have another pure or dualclassed or specialized mage in your party you'll only experience casting power as if from a level drained caster.
If you want a cleric/mage multiclass cleric/illusionist is far better, the extra mage spell per day and level for specialization does make a difference.
Skalds are great for supporting physical combat but if you pick one as 6th character you should dual your first in order to get access to high level mage skills during the game.

The more I think about the Skald, the more I'm not liking it. The bonuses are nice, but it seems to be lacking in overall contribution, so I think pure mage will be the way to go.

What is a good level to dual from a cleric to a mage? I may make the cleric/mage a pure mage, then figure out the final slot again. :p

Mainly, I'm just looking for a good, solid, balanced team that is fun to play.

Good point on the weapons GoatBoySteve, I didn't even think about that. I usually do dual axes in other games, because axes are cool, but getting some backstabs in could be beneficial.

Personally, I'd go a multiclass cleric/mage (or better yet, cleric/illusionist) or abandon the combo altogether. With casters you generally want to get those higher level spells and dualing from a cleric to a mage is going nerf the cleric portion pretty hard.

If you decide to replace that slot with a pure mage, I recommend going Conjurer kit, Sorcerer, or starting out with a few warrior levels and dualling over. Conjurer's get extra spell slots, but don't lose out on any of the better spells, sorcerers have a different memorization mechanic that is interesting and potentially powerful, and a mage with even a few levels as a warrior will have better HP, STR, Thac0, and weapon proficiencies without being far behind true pure class mages in levels.