I think I once saw a feat that gives you +4 caster level in a class up to your hd, same as the Magical Knack trait which gives +2. These are just caster levels, right, they don't give you access to higher level spells as if you progressed in that class?
Trying to find something to work with wizard, which is kinda boring after 5th level, and most of the prestiges seem to be super specific or evil.
Practiced spellcaster from 3.5. I don't believe there is a pathfinder equivalent, but I have been wrong before.