If you need to access a Playa field from within another Playa field, the only way to go about that is through an embedded template:
<h4>My Favorite Bands</h4>
<ol>
{embed=bands/_members entry_ids="{favorite_bands:entry_ids}"}
</ol>
{exp:channel:entries channel="bands" fixed_order="{embed:entry_ids}"}
<li>
<h5>{title}</h5>
<p>{band_desc}</p>
<h6>Band Members</h6>
<ul>
{members}
<li>{title}</li>
{/members}
</ul>
</li>
{/exp:channel:entries}