Sadly, there's not much of anything around the Warhol museum. There's stadiums.... and, uh, not much else in the area. The Warhol's cafe is quite good, though, and veggie friendly. There is Stedeford's Records on East Ohio street, but finding the treasures inside take time. Good hip-hop vinyl tho.
Pretty much everything you want is in the East End. Jerry's (2136 Murray Ave, 15224) is an amazing vinyl store for all genres that people travel from other countries for. Brave New World (in Oakland) handles punk / hardcore / hip hop, Pauls CDs on Liberty ave is excellent for everything else. 720 Records in East Liberty has a lot of club / hip hop / reggae.
Oh yeah, bikes. Kraynicks (Penn Ave) is fantastic for vintage stuff. You could blow the four hours there, no prob. Also, Iron City bikes (331 South Bouquet Street, Oakland) has used stuff, but I haven't been there in a while. All that stuff should be Google-Maps-able if you want to get a better idea of where everything is.
My personal rec - Warhol / (several excellent restaurants en route) / Kraynicks / Jerry's / parkway to Saxonburg.