What zone are you? 7, 8? You have tons of options because it is full
sun, and depending on how much water it gets. Any of the shorter
Salvias, verbena (depending on your zone), mint, lavender, hardy
prostrate rosemary, (all of these will attract birds and butterflies
and are perennial).
ps. you grow your hostas in sun? Ours will only grow in shade. (because
of the summer heat).