Currently, i am not using AU for I am going for a Grim Tales campaign, so no regular D&D classes and races. However, if one day I go back to my regular D&D campaign, here is what I will use and do:
Books used: Basic D&D 3.5 + Unearthed Arcana (D&D) + D&D Psionics 3.5 + Psychic's Handbook (Green Ronin) + Arcana Unearthed (Monte).
All of this makes for numerous classes and races. However, to give some flavor I restrict some classes to some races:
What I will use: 3.5 psi classes and Akashic only allowed for giant race (a mixtue between Xpsi half-giant and AU giant). Psychics only allowed for dwarves, humans, and half-humans. AU Witches only allowed to gnomes, halflings, and elves. Arcane Magic: Wizards (including many UA variants) are for humans; Runethanes are for Dwarves; Magister and Mageblades are for elves. Wariors: humans and half-humans are typically fighters, paladins, and rangers; halflings and gnomes warriors are rather of the unfettered class; elves are typically champions (treated as faerie knights) and totem warriors (especially hawk and wolf totems).