600 used speakers?

You'll get a lot of good advice, and at $600 there's a great selection to pick from. Many will suggest the Magneplanars or Thiels, both worthy contenders and certainly worth considering if they meet your "good looks" criteria. If you'd prefer a smaller and more traditional enclosure, I would suggest you get a very good monitor with somewhat limited bottom end and add a subwoofer when economics allow. Allow at least $200 (shipped) for good used speaker stands. Should you choose to go this route I would include the Totem, ProAc, and B&W speakers on your short list. Regardless of the style of speaker bear in mind the lower the sensitivity specification of the speaker the more difficult it is to drive, limiting how loud you can listen to "Dazed and Confused". Specific models can be selected by browsing the used ads here on the 'Gon. At the main page, very top, type in Totem (e.g.)and up pops all the available Totem speakers for sale here on the 'Gon. You have the makings of an enjoyable system, best of luck. Jeff

For B&W a pair of the original CDM-1 bookshelf speakers. They are actually the best CDM-1 version for music because of the first order crossover not found on later versions. Also the P5 floorstander.

You might get lucky and find a used pair of NHT 2.5i's, I've seen them used for 700 or so. They're very slender, and fairly tall.
They will also play pretty deep (more so than most low-mid price subs), a must for Zeppelin! They sound great with rock music in gerneral, I have a pair in the bedroom.

Not the best for hard rock, but for the more acoustic and vocal side (Bonnie Raitt, some Dead & Clapton, etc.) you'd be hard pressed to go wrong with Vandersteen 2ci or ce, of which you should find plenty here and on ebay at your price point. They will always sound good as/if you upgrade to better electronics. They are tall and reasonably slender (about 48" x 16"). They go reasonably low and would mate fine with a Vandy sub if you wanted more extension.