About Bioware, the Aerie romance is still by far the best game romance I've seen anywhere.
Lots of dialogues, interesting developments, it was just really well written and interesting and had a satisfying ending, too.
The Jaheira and Viconia romances are most likely also really good, but Jaheira is frankly just annoying me, and Viconia as an evil character is just too much of a hassle. Would have loved to get a helmet of opposite alignment in BG2 unfortunately that one just doesnt exist there (the BG1 addon had one, at the end of Durlags dungeon).
You can change Viconia's alignment if you romance her. Doesn't happen until Throne of Bhaal, so you have to wait a while, but it can definitely be done without the helmet. Unfortunately there is no way to stop Jahera from being an annoying nag.