[Philos]

Hi Krunchy,

Personally, I would go with #1 primarily for the dual class thief/mage. Party #2 has 2 magic users but they are both multi class. I think with #2 you may hit a point (not sure where that might be if you choose to do HoW and/or TotL) where you'll find yourself saying geez I wish I had (pick name of any good 6th/7th Mage) level spell. A multiclass xxx/Mage gets to 11th level and 5th level spells in a decent time but (IMHO) they hit a stiff wall as it takes 750k (since you are splitting the experience between two classes) to gain a level in mage after that. A fighter/thief/mage is even worse with a 3 way split (1125k xp to rise in mage). The other classes of course will go up faster but it will seem like "forever" before he/she levels in mage. This is one reason I don't like to use Aerie in BGII, she is a cleric/mage. Even doing all the add on modules you will likely finish the game not long after you get a 7th level spell, probably even before with the triple class. Would hate to miss putting some of those 7th level spells to a lot of use, not to even mention the really killer 8th and 9th level spells.
A character can get to 7th thief pretty quick and that is more than enough to handle the thieving requirements in IWD (sadly). But I have a soft spot for gnome fighter/thieves (love that helmet Conlon sells). I know this would mean more thieving levels than necessary, but I would be tempted to go with a gnome/thief and a plain mage. Just my preference.
But of your two parties I think number one is the better one. BTW, I really like Cleric/Rangers, they get druidic spells mixed in with the normal clerical ones and much faster than a regular Ranger. Sure is nice having a Cleric that can cast Entangle at 1st level.