title: How would you design a good search UI?
body: <p>I want to provide my users with an 'advanced' search engine.
  I basically have a lot of search criteria to chose from :</p>
  
  <ul>
  <li>some are very simple/common and will be largely use (ie time period, item id)</li>
  <li>some are a bit less mainstream</li>
  <li>and some won't be used a lot, but I still want to provide them</li>
  </ul>
  
  <p>Overall, I have around 30+ criteria to chose from</p>
  
  <p>The result is a dataset which I display in a grid.</p>
  
  <p>I've search for inspiration on internet, and even <a href="http://www.google.com/advanced_search?hl=en" rel="noreferrer">google</a> doesn't seem to have a nice solution for advanced search.</p>
  
  <p>I've designed this kind of tools in the past, and I wasn't really pleased by the result, although the user were eventually able to use it quite effectively.</p>
  
  <ul>
  <li><p>Do you think the search panel should be visible all the time (ie displayed on top of my result grid) or available in a separate form (which would let me use more place for all the controls)</p></li>
  <li><p>Do you think it's better to display all the search criteria, or to let the user click on 'advanced' if he wants to see/use more criteria</p></li>
  <li><p>How would you organize the criteria? by usage frequency, or rather by area (ie. criteria related to user, to location, to time, etc.)</p></li>
  <li><p>Where should I put the 'Search' button? next to the more common search controls, or at the bottom, or both?</p></li>
  </ul>
  
  <p>And more generally, do you have tips you want to share on how to design a nice search UI ?
  What kind of functionalities do you usually miss in this kind of 'advanced' search engines?</p>