TerriblePurpose: Are you a min/max type of player? If so, I could probably make some suggestions, although if you're willing to multiclass one or two characters at all you'd have a more effective party. But you can certainly get by with single class characters.
I prefer simplicity, as in that each party member has certain main role in the team, and not multitasking too much. Hence I prefer not making it more complicated with multiclassing, trying to figure out when is the right time to jump ship, how much I should disperse ability points (e.g. giving a Fighter also high INT just because I am going to make him a sorcerer too) etc. Maybe the only exception is that I prefer some having also the ability to heal in addition to cleric (just in case cleric gets incapacitated, or several team members need healing at the same time), like a paladin and druid.
Oh and it is nice too that cleric can apparently melee fight pretty well as well, besides just healing. Even without multiclassing.
I am not looking for a perfect powergaming team (which probably needs multiclassing, and possibly having fewer party members to make them level up faster), but naturally I don't want to make stupid characters either, like a weak fighter or a wizard with low intelligence.
Anyway, I think I finally nailed it and got to make a party I can go with. Good thing someone reminded me of adding a rogue, at least in the first IWD it was very important in order to find and disarm traps, being a scout to see enemies before they see us etc.
1. Male Human Paladin (of Ilmater)
Lawful Good
Strength 16
Dexterity 12
Constitution 14
Intelligence 3
Wisdom 15
Charisma 16 (because he is the party leader)
2. Male Shield Dwarf Fighter
Chaotic Good
STR 18
DEX 18
CON 20
INT 3
WIS 16
CHA 1
3. Female Half-Elf Cleric (Battleguard of Tempus)
Chaotic Good
STR 18
DEX 16
CON 18
INT 3
WIS 18
CHA 3
4. Male Moon Elf Wizard
Neutral Good
STR 10
DEX 18
CON 16
INT 18
WIS 11
CHA 3
5. Female Strongheart Halfling Rogue
Chaotic Good
STR 14
DEX 20
CON 15
INT 12
WIS 12
CHA 3
6. Female Half-Elf Druid
Neutral Good
STR 12
DEX 16
CON 17
INT 10
WIS 18
CHA 3
Some points I think (hope) I learned during the process:
1. Fighter types, and others too, do benefit from Wisdom, so it shouldn't be set to minimum to non-clerics/druids. Having it a bit higher helps against certain enhancement spells and such, I guess. So I left it to at least 10, or higher, to everyone. And max to clerics and druids of course.
2. Intelligence for non-wizards: the FAQ I read was contradictory. in one place it said that every party member should have INT of at least 10 (and higher for Wizards) because otherwise you get less skill points. But at the same time, the example party in the FAQ did have INT 5 characters and the points were used elsewhere.
To me it seemed that only few classes benefit from lots of skill points. For e.g. my Fighter, I didn't really see any interesting skills to improve that much, so it is ok it has less skill points. Then again, Feats are a different matter...
On the other hand, a Wizard and Rogue have several important skills to improve, related to magic or thievery and such, so I gave them more INT (Wizard needs high INT anyway).
3. The FAQ mentioned that in some quest you need a character with INT 16 or higher, hence I decided to have a Wizard instead of Sorcerer, as a Wizard benefits from INT also for spellcasting. Then I didn't have to divide the points that much between INT and WIS.