In reply to steve.aisthorpe:
This is the circuits guide I'm on about.
http://image.bokus.com/images2/9781594857706_200x_fontainebleau-climbs-a-gu...
Last time we went we had a whole plethora of books and this one, for me, was the best bet for getting to the parking, finding the crag, and finding your way to a particular numbered circuit problem.
From there we used the 7+8s or the description from bleau.info (it normally shows you a picture of the problem and the accompanying text will say "to the right of blue 32" which is enough to get you there) to find a particular problem we were interested in.
Just to be clear on why this method worked for us. The 5+6s and 7+8s books are great, but finding your way around a boulder field can be difficult if you can't identify where you are on the plan to begin with. These books mark on selected circuits on their topos and you kind of need to use these to get an idea of where you are on the plan.
As for Font sandbags, in my limited experience of climbing there, I honestly can't think I've climbed any (I'm sure I must be wrong, I'll try and think of some). Things seem fairly graded, but Font is a very popular destination for people who are relatively new to bouldering and may only have climbed indoors, or else are lacking in technique. If this is the case, you're likely to get shut down.
Post edited at 10:36