Is it a good idea to lay cedar chips up against the perimeter of the house to protect against brown recluse spiders?
Not really. In fact it's never a good idea to lay any kind of mulch up tight to the foundation. You see, all mulch will do is to preserve if not create heat on it's underside (where it contacts the ground). This heat will no doubt attract insects. And when you have insects living right up alongside the home, the odds of some getting inside are greatly increased.
Now if you must have mulch like cedar chips or pine straw up tight to your homes foundation, be sure to apply some BIFEN GRANULES to it every 2-3 months. This way the Bifen will kill off all the insects that attempt to move into this prime real estate.