[SixOfSpades]

As far as Jaheira goes, I should note that Druids are great.....in BG2. In BG1, however, they're handy to have around until you can find yourself a decent Cleric--which you have already done. On the Wizard front, you will NOT absolutely need a Mage at all, and in my opinion, you're actually better off playing the first half of the game without one--hack & slash will work quite well for most of the game. About "too many Rangers"....If Basrah has good Tanking stats, you don't really need Minsc. If Basrah prefers pumping the bad guys full of arrows, you don't really need Kivan. But, as I said, physical combat rules in BG1. One thing, though: You are going to meet people whose ablities are going to sorely tempt you to drop Kivan or Minsc. As for Imoen, do NOT Dual her unless you have another very competent Thief to take up the slack.

My ideal party:
1 Tank (usually the main character)
1-3 Backup Tanks
1 Cleric
1 Mage
2 Thieves
Note that that's as many as 8 people. Find people who can do double duty: A properly equipped Priest can also serve as a backup Tank, you've seen that Imoen can be a Mage as well as a Thief, etc.

Now, all of those are powergaming considerations. Let's roleplay now:
Edwin is at his best with Minsc and Dynaheir in the party as well. Edwin hates the other two, and they bicker and argue all the time. There are also 2 Dwarves in the game, and it's amazing how 2 members of the same race could despise each other so much. There's also a Female Human Fighter floating around, who has some mean banter with a Bard, and you might happen across a Halfling Thief who has something going with Edwin. Some people can't stand Xan, but I happen to think his depressing attitude is funnier than heck.