What is the most semantic way to display a street address in HTML?

You could use the hCard Microformat to describe your address. The advantage of Microformats is that you can use them in your existing documents to enrich them.

Here’s an example derived from the example from the Microformats wiki:

<address class="vcard">
  <span class="adr">
    <span class="street-address">169 University Avenue</span>
    <span class="locality">Palo Alto</span>,  
    <abbr class="region" title="California">CA</abbr>&nbsp;&nbsp;
    <span class="postal-code">94301</span>
    <span class="country-name">USA</span>
  </span>
</address>