Depends on the type of antennas you're going to use.

If my antennas are rubber duck/rubber duckies then it would be good if the antennas are pointing towards the floor.  If you have the articulated antennas of the above-mentioned varieties then you can mount the WAP on the and bend the antennas to point to the floor.

However, if you have the patch antennas then you will need to ensure you go through the signal pattern to know whether the antenna needs to be patched on the wall, ceiling or pole.