So to levitate, is it...
1: Standard action, cast spell
2: Movement action move up/down 20'
or is it...
1: Standard action, cast spell, move 20'
Either this is trivially simple, or nobody wants to touch it.
In the spell description:
You can mentally direct the recipient to move up or down as much as 20 feet each round; doing so is a move action.
Casting the spell is a standard action. Mentally moving someone, including the caster, is a move action.
The Oracle in my group uses levitate all the time.