I used to like using Jaheira in BG1, but now that she is a romance option in BG2, I usually don't take her.
It just kinda wierds me out, since she was mentor, and bit of a mother role to my characters in BG1... To turn around after Khalid dies (Yes, I liked Khalid, darnit) and sleep with her is just icky.
Reeks of a Edapis (sp) complex to me... a psychologist's field day.
This is just with Male characters, which I normally play with. The couple times I have played a female character, Jaheira has accompanied me.