Well, as far as Alistair is concerned, I'll refrain from commenting more on that other than saying he usually tends the campfire with Morrigan, and that's that.
I usually play with a mage (which might be my PC, or she might be a rogue), and I take another rogue, dog, and Shale. I never found myself wanting for a tank. I use tactics so that my archer and/or my mage are protected by the rest, set them all to swallow potions when <75, and either my PC or Wynne are specialized in healing.
Both rogues are respecc'd, and they are awesome. Next time around I'll plan on seeing if I can do the same for Sten. Turning him into a decent warrior needs to much time and patience without a mod. At least I find it nerve-wracking in a sense.
Later on I take Oghren, but I must be doing something wrong with the poor guy, he dies pretty quickly, and my mage/Wynne practically has to baby-sit him. I take him, because I really like him

As for Bhelen vs. Harrowmont, in my first play-through, my mage had absolutely no clue about dwarven society. How could she, she was a virtual prisoner all her life. So all she had to go on was questioning, listening, and drawing her own conclusions. It ended up by her deciding that of two bad choices, Bhelen was not quite as bad as Harrowmont.
Same with Branka vs. Caridin. Branka was a raving lunatic, the anvil far to prone to be used in a very, very bad way, and Shale (one of my favorites) sided with Caridin. Since Shale knew more about golemnism than my mage and Branka combined, she sided with Shale and Caridin. It helped that Oghren also seemed to think using the anvil was a bad idea. The only one who was against its destruction was Zevran, but to my surprise he actually listened and understood my mage's reasoning and backed down without any kind of disposition hit whatsoever.