If you're brand new to CRPG's then something like KOTOR 1 and 2 might be better than Baldur's Gate 2 or Planescape. The latter are both phenomenal games, but they're harder to get into due to not very user friendly interfaces. The KOTOR series though is more accessible.
Plus the writing of KOTOR is equal I think to Baldur's Gate 2. And KOTOR 2's writing is close to Planescape's. (Which makes sense as they were pretty much done by the same people).
If you play KOTOR 2 though make sure to get the restoration mod, as Obsidian wasn't able to finish their game, and a bunch of content was left out that later got restored.
Of course play KOTOR first before KOTOR 2.
Also highly recommend Vampire: Bloodlines, and Fallout.
edit: oh yea and also highly echo Mask of the Betrayer. It's an expansion to NWN 2 but you don't really need to play the original to enjoy the expansion. Absolutely phenomenal though, and the closest to a Planescape sequel we've seen.