If you add a level of Paladin, add three. Apparently, Divine Grace is bumped up to 2, but even in 3.0, you got the Immunity to Fear Effects at second level and Turn Undead at 3rd. Now, with only three levels of Paladin, your turning rolls will suck... but that's why you take Power Attack and Divine Might. If you're a Sorceror, you can combine Power Attack, Divine Might, and/or Smite Evil with True Strike (and a greatsword) to do an amount of damage Sorcerors simply are not intended to deal in melee.
Personally, I like adding two levels of Monk to just about everything. I rarely play non-Lawful characters, I dislike armor, and those two levels are just full of nifties. I'm surprised noone else suggested it... it's perfect for arcane casters.