Thank you all for the help. I think I shall keep my Paladin as a nice monogamous type with Aerie but it's interesting to see how to tweak the game.
I've stuck the official patch and the baldurdash fixpack on okay (Which includes the fix for the Jaheira romance I think) and am debating the Ascension add-on.
BG-II/ToB seemed to be the CRPG with the most intra-party interaction (even if you exclude the player-NPC romances) it's a shame that (as far as I can see) none of the others on the market come close.
I shall be a little sad when ToB is over. Le sigh...