Imho you need a little more muscle. I tend to employ three 'tanks' but then my style favours melee combat. The three I have at the moment are:
Aasimar Paladin - 14 (with Holy Avenger

)
Half Orc Barbarian - 15
Half Elf Monk of the Broken Ones - 15
The party is rounded out by:
Human Morninglord of Lathander- 15
Human Evoker - 14 (should be 15 but she died at a critical moment and did not get to partake of the xp on offer).
Tiefling Thief - 14.
I do not think there is any better cleric. As you say the domain spells are great - try Sunbeam and watch your enemies turn into crispy critters.
The mage follows the usual pattern, magic missiles, fireballs, a few summon shades and some of the more brutal necromancy spells. The conjuration spells are a bit of a miss but the cleric can summon elementals/monsters. Losing divination is no problem, the cleric can cast Invisibility Purge. Identify is next to useless if you give your mage sufficient points in Knowledge/Arcana.
I like to keep a single class thief with massive dexterity for those missile attacks. I like a good sneak attack too, especially if the enemy has a high level mage!
The only one I am not sure of is the Monk, I may take a fighter/ranger next time. However, he has just acquired the quivering palm ability so I shall have to see how that works out.