I tend to change equipment depending on what i'm fighting, you've gotta use all those quickslots for something. Immunity items don't seem as good in NWN2, probably because so few enemies actually use death magic and other dangerous spells/abilities. Back in NWN1 you'd crap yourself any time you had to face a water elemental or a bodak if you didn't have death magic immunity, and they were low level creatures. It meant that your saving throws were actually important so any items that boosted them were useful.
Typically though, once you have protection against Death Magic, Mind spells and knockdown and have something with good spell resistance, you can put the rest in AC and use whatever the most powerful weapons available are and you'll be fine against anything.
I think for the later stages in the game your equipment over-shadows your actual character attributes and you become almost invincible due to the amazing items you use.