Can anyone let me know what the best plan of action is for this?
The best plan of action is always the same when you "extend" a network.....
That would be to locate each AirPort right in the middle of each area where you need more wireless signal coverage......and......connect each AirPort back to your "main" AirPort router using a wired Ethernet cable connection for each device.
If you cannot run the Ethernet cable, then powerline adapters might allow you to send a coded Ethernet signal over the existing AC powerlines in your home. The theory with these devices is that you already have the wiring in place......you just need the adapters. Unfortunately in practice, things do not always work as well as the theory suggests. And, there is no way to predict how well......or, even if.....powerline adapters will work in your home until you try them out in your home.
Any computer / electronics superstore will have a selection of powerline adapters from which to choose. Talk the salespeople there to find out which product they would recommend for your home......and then make sure that you understand the store's return policy before you buy.
The least desirable plan of action to extend a network would involve trying to use a wireless connection between AirPorts. Although it is possible to have more than one AirPort to extend the signal.....each AirPort must connect directly to the "main" AirPort in order for things to work correctly. That means that you cannot extend a network two times.....or, in other words, extend the signal again from an AirPort that is already set up to extend the network.
When you try to extend using a wireless connection, each "extender" will receive a much slower and weaker signal....and that is all that it can extend, so on average, you should expect to lose about half....or more....of the potential speed on the entire network when you extend a network using wireless connections. With cement walls and ceilings, the signal speed loss is going to be much greater, so trying to extend using wireless connections for your home is definitely not recommended.
The investment to run Ethernet cabling would be worth every penny, in my opinion.....if you can consider that option.
