I agree on the Monk/Sorcerer/Paladin... but not for the same reason.
Paladins bonuses I beleive come at 4th level BUT I dont care his/her best bonus comes at level one: Being able to use the Holy Avenger + Monks can use the Gauntlets of thundering clap (er something) that adds 2 attacks per round... Now you have a level 20+ sorcerer that in a pinch weilds the best sword in the game and gets 5 attacks per turn with it...
A little improved invis and you got a COMPLETELY unstoppable solo character. Human/Wild elf would be your only options here I beleive. I like human better. Never been a big fan of High Dex spell casters I would rather have the hitpoint and concentration bonus from high Con.