I'm an arcane caster using the Vest of Mysterious Conjuration, which gives 3/day the ability to burn a spell to cast Summon Monster x of the same level.

I have level 9 spells, so all levels of Summon Monster are open to me. What's considered the best monsters to summon. Ideally, I'd like some idea of meat-shield, distractor, etc.

I think avoral guardinals are good for healing the party (Lay on Hands ability). Are there any 'utility' monsters worth summoning of 6th level or lower? Healing or things that can cast 'Solid Fog' or other crowd control spells.