This is a classic. It concerns an urgent message from a student to his parents. The cache is at North 37.28.XXE and West 122.12.SMX.
You will notice that there are 8 separate letters in this puzzle. You will also notice that the letter X does not appear in the puzzle. X = the lowest digit not appearing in the puzzle. The solution is unique.
A couple of notes:
**Most grownups can solve this in about 5 minutes or less. However, this is an excellent puzzle for kids. I suspect most middle-school students will take about half an hour to solve it. Most importantly, they usually will thoroughly enjoy the effort. It is also a good introduction to this sort of puzzle (and number theory in general!). You might want to have the younger members of your teams work on this and direct the search.
**I really don't think that I should have to mention any of the following, since I firmly believe that figuring this sort of thing out is part of the puzzle. However, I try to play fair, and I don't like getting unpleasant emails. You are allowed to assume the standard conventions of this type of puzzle. Namely: Every letter stands for a single digit; every letter stands for the same digit each time it appears; every digit is represented by a single letter (i.e. one-to-one correspondence between digits and letters); naq arvgure Z abe F ercerfrag gur qvtvg mreb. I put that last bit into rot-13 since realizing this fact is fundamental to solving these types of problems.
The cache is small plastic container. I probably could have found a spot closer to the nearby in-theme establishment, but I opted for something in the usual location to protect both the cache and the cachers. The FTF prize is a Sacagawea dollar. It didn't fit, so I taped it to the bottom.
If you like this sort of thing, try "SAVE + MORE = MONEY". There are three distinct solutions. (Actually six since V and R are interchangeable, so it comes down to your definition of "distinct solution.")