You may find this thread helpful.
Missing person spread?
http://www.tarotforum.net/showthread.php?t=2115
That thread includes two spreads you may like...
Thirteen's World Spread
Use the World Card as your guide. Put a card at the center to stand for your missing person (a court card you feel is them in a nutshell). Then lay out the cards as follows:
4*********1
*****0****
3*********2
#1 is Scorpio--where are they at emotionally, psychologically? Angry? Sad? Numb?
#2 is Leo--who is with them? Among friends? Enemies? Strangers? Family?
#3 is Taurus--what is their physical location? Where on the planet are they standing? Or are they on the move?
#4 is Aquarius--where are the planning to go? Do?
And then add a 5th card to cross the one at the center. Let that one be "Advise?" (i.e, should you keep searching? Call? Worry? Relax?)
The Lost & Found Spread (from "Power Tarot" by Trish MacGregor & Phyllis Vega). It is apparently intended to locate lost objects, but it could be used for a missing person.
It is laid out as follows:
------------------------10------
1----3--------6---------9------
--------------------------8------
---2----4----5----7------------
1. The object (in this case, the person) that is lost
2. Something you need to know about this loss
3-4. Where to begin your search
5. Who or what will help
6-7. Factors to be considered in your search
8-10. Outcome
There's also VWH "Just The Facts" Spread
http://www.tarotforum.net/showthread.php?s=&threadid=30585
You may be able to modify my "Be Like Nancy Drew" Spread
http://www.tarotforum.net/showthread.php?t=80106
And if you want a short, simple spread you may like
LadyBlackRose's 3 Card What You Know Spread
http://www.tarotforum.net/showthread.php?t=52784