You mean you don't use the Ring of Fire Control, the Ring of Free Action, or the Rings of Regeneration?
Here are some suggestions:
Me (Mage) - Ring of Wizardry, Ring of Acuity
Mazzy - Ring of Battle Skill, Aegis of Torment
Jaheira - Ring of Gaxx, Ring of Holiness
Anomen - Ring of Aravorn, Ring of Gaxx
Jan - Ring of Acuity, Ring of Wizardry
Kelsey - Ring of Wizardry, Ring of the Ram
I assume that Anomen and Jaheira are your frontline fighters and Mazzy mainly uses ranged weapons. I always give the Ring(s) of Gaxx to my frontline fighters because they need the most protection and they always take the most damage (so that's where regeneration helps the most).
The Ring of Battle Skill and the Aegis of Torment would help make Mazzy a better melee fighter, especially if you can raise her CON by another point (resulting in a 20 with the Aegis of Torment). If you equip her with a girdle of giant strength, then you could make her a frontline fighter, as long as you give her proficiency points in something besides Shortsword and Shortbow and equip her with a decent weapon.
I don't try to buff up my spellcasters all that much; I keep them out of melee and let them cast spells. The Ring of the Ram has its uses, so it would be nice to use that second one, but I'd rather use all of the Rings of Wizardry and Acuity and get all of those extra spells.
If you have the Ring of Free Action, I'd consider giving it to Jaheira instead of the Ring of Holiness. And there are definitely times when I like to use Rings of Fire Resistance and the Ring of Fire Control.