when tim sale and jeph loeb team up it's gonna be good. long halloween, superman for all seasons, spidey-blue, daredevil-yellow, hulk-grey...all good stuff.
i'd also recommend superman-secret identity. awesome story of how superboy-prime should be instead of the whackjob lunatic he is.
superman, up up and away was good.
batman; madlove is awesome. not only is the main story great but it has one of my favourite two face stories ever.
jms' recent thor run was good stuff.
all star superman is amazing.
i've read a few trades of astro city and while it isn't main stream superheroes they're pretty good.
for green lantern i'd recommend at least secret origins, rebirth, and then from sinestro corps war onwards, the 3 volumes between rebirth and sinestro corps war were mainly reestablishing hal jordan's place.
dini's run on detective comics was good, kinda a whatif batman:tas was made into comics with a little more freedom. lots of quick contained fun stories.
welcome to comics, say goodbye to any cash you may have