Sonic Youth - Goo
Scratch that, get Evol. Or Sister.
And you may as well get Daydream Nation too, since that's the 'hit' album. Ignore Goo. For now.
Also, as far as pavement goes, Brighten the Corners is the most instantly catchy pavement album, easily the most accessible. Start here.
Slanted and Enchanted is definitely a fun album.
Wowee Zowee the most varied. It's also the hardest album to get into, but has some of the best work they ever did.
Crooked Rain Crooked Rain was pretty good. The songs are catchy, I'd say it's the second most 'accessible' album.
Terror Twilight was super mellow and fun to listen to. This is the 'pleasant' album that isn't too intrusive, throw it on when you have friends over, they'll like it.
If you want to get into pavement, don't get the 'extended' versions of the albums. They'll just overwhelm you and make it much harder to get through the albums. Also, as a general rule, if it's british and it's in this music forum, it's shit. The exceptions are bands from Scotland.