In AD&D 2E, victims under the effect of Charm person/Domination may only try to make another saving throw once per 3 weeks if their intellect in around 10-12, even the most intellect people(19+) may only try to break the effect once per day, the spell last forever if not saved or dispelled.
In Baldur's Gate however, Charm person, Dire charm and Domination last too short(5 rounds and 8 rounds), and there are equipments that offer way much stronger charm effect, two cloaks that one can charm person once per day, and another has 40 charges, also there is a bard tool can cast Domination for 20 times, ALL THEIR EFFECTS LAST 12 HOURS AND WON'T TURN THEIR VICTIM HOSTILE.
I think lots of players don't even know, that most NPCs in Baldur's Gate have unique dialog if they were charmed, some of them will give you gold or jewelries, some of them will update your journal, and of course they will let you take anything within their house and all of them is fun! Such a shame they didn't carry this to Baldur's Gate II though.
Anyway, back to the topic, I think charm spells last too short, there are even better spells to cast in THE SAME SCHOOL(Sleep, Hold Person, Hold Monster, Feeblemind), since charmed victims can't leave their current area and will turn hostile after the spell is end, the proper duration of charm spells should be at least 24 hours, what say you?