I can really, really recommend the Catrix cat scratcher. Very easy to assemble (absolutely no screws, hammers etc needed), modular so you and construct your own design, the cats love it and you can construct lots of 'resting' places i.e. the square soft cat bed and the paw (wouldn't recommend the hammock).

Easy to clean/hoover - detachable cat bed thingy for machine washing and you can hang/tie things off it for cat fun!

Replaceable parts when cat scratches it to bits.

And best of all cats really, really love it and use it to bits!