Signal through (or around?) bricks

I'm setting up a motel wifi network. The motel has a layout per the picture attached (sorry for the crudeness). There are two APs, one in the office and another acting as a repeater in a remote building. You can see the antennae and their coverage areas. All antennas are patch panel, 14 - 18DBi. In the wooden buildings I have no signal problems at all. In the brick buildings, I have no signal at all



To make matters worse, the brick units all have a bathroom next to the door, and the door is the only "non-brick skin" to the outside. Thus, door aside, the signal has to go through at least two brick walls. The roof is not brick (!) and out the back of each unit is a big, 2m square window (set in a brick wall).

What are my options for getting wireless into the rooms? Reliability is the primary consideration, though an antenna in each room seems a bit ridiculous. On that note, can you buy "antenna multipliers" which take an antenna signal, repeat it and push it across to more antennae?

Put the units in the attic and straddle the brick walls. Look for something that supports PoE and dual radios for increased bandwidth. Echotech Wireless is the cheapest I have seen. Go for the high-power units but keep in mind the range from the clients.