I've never chosen an "alignment" based party because it's impossible. This ain't D and D. It's a game world where morality is as fixed as the weather. And, personally, I enjoy netting some disapproval from party members, enjoy the arguements and disagreements because it adds reality to the game.
I found Morrigan disapproves of damned near anything that I did. However, because there's so many Morrigan friendly gifts in game, it is easy to return to her good graces in no time. Unless you are playing a mass damage oriented mage, there are a few quests where I find her indispensable, such as the blood mage warehouse in Denerim, where basically, the place is infested with heavy hitting mages, and you need someone who can take out or incapacitate as many and as quickly as possible, else you're very dead, very quickly.
But don't stick with one single party set up. Rotate them frequently, because different quests and areas require different sets of talent. The only exception to this rule was Alistair, as he was the only tank in game. Because I find two-handed abilities useless, and they take too long to activate and execute, neither one has every functioned well as a tank, despite giving them even better armor than Alistair. Thus, I only bring them along when a mage is not needed, and there's alot of heavy-armored enemies than need heavy-damage. Unless you are playing a shield-warrior yourself and thus can function as your own tank, I find that the only two necessary constants, party-wise, are Alistair and a rogue, because damned near every area in game has locked boxes, and many have traps, too.
But the most important thing about rotating your party, in my opinion, is the banter, because the banter is hilarious, and new ones open up depending on who is traveling with you.