I'm almost reluctant to post this, as the reason a patio's so nice is that it isn't packed to the gills on one of these nice spring days.
My favs right now (because I unfortunately live north) are Skishores, Manuels for happy hour, NxNW, Green Mesquite and Freddie's Place. Honorable mentions are Fliphappy (well sort of a patio), Polvo's.
It broke my heart when Eddie V's closed in their patio at the arbor. Now that front part is always empty. Yes, it was "in a parking lot" but it was always full when it was al fresco. I used to love to sit at a table out there and people watch.