Monk Shifter: Taking a few levels in Monk means I'll need to invest enough points in STR, DEX and CON to get decent unarmed feats (like Cleave) but sacrifice the extra Wisdom and extra forms later. It also means I might not be able to invest in enough levels, feats or attributes to get some of the spectacular forms later. So I'll be a better all-around fighter, but won't be as neat a shifter.
In NWN a monk gains Cleave at level 1 even if he does not have str 13+ nor power attack. If you take 6 levels of monk class you will automatically gain Improved Knockdown (again, regardless of prerequisites). So, Monk/Druid/Shifter build does not need much attributes other than Wisdom. Having descent Dex and Con will be useful, though.
In regard to survivability, monk build is much tougher as it gains monk AC bonus even when shifted, and even if he was wearing some armor in his original form. When shifted, only the property of the original armor is transferred and the shifted form is considered non-armored.
In SoU to HotU level range, the most useful combat forms will be Minotaur, Drow Warrior and Rakshasa. Rakshasa is great as it can ignore level 0-8 spells and has bludgeoning weapon, which is useful against some bone-based critters. Undead shapes are good but you may suffer painful defeat when meeting some opponent clerics.
