Clarifications and fixes should be the main aim, IMHO.
As stretch goals I'd add more monsters from the Monster Manuals/Fiend Folio as the OGL allows.
Maybe a single class Bard class, as the one that appeared in Dragon Magazine.
I'd say no to extended level caps, no to cantrips, no to more class options for demi-humans....
Basically nothing from the Unearthed Arcana onwards.