WIFI extending

In a very large house with three separate electrical wiring systems,
what is the best way to extend the WIFI?

As I discovered today The disjointed wiring system means I can't use the
power line connectors which sends the signal through the power cables.

I have not had very good experience with an extender similar to this:
http://www.amazon.co.uk/Wireless-Rep...=wifi+extender

I am considering buying a couple of these inexpensive routers:
http://www.amazon.co.uk/Wireless-Rep...=wifi+extender

Would I be able to use that as an extender? How would I configure it?
I guess I am unsure of the terminology for using a router as an
extender. IN my current router I see several kinds of new connections:
PPPoA, PPPoE, Static, DHCP, Bridge and Clip.

Which one would I use to configure the routers as extenders? and is it
the best solution given that the other simple extenders are not going to
work.