A quick warning: 5GHz signals have more bandwidth but less range. You may need *more* base stations to get coverage.
That seems to be the consensus among the replies so far. Crap.
My current plan, for what it's worth, is to wait for 802.11ac to stabilize and then look at doing a major home network upgrade once laptops and phones start supporting it.
I just this year reconfigured the routers to 802.11g only because until then I had some old equipment that still connected occasionally. Waiting until a) 802.11ac gear becomes affordable (I paid about $40 each for my WRT54g routers), and b) enough of the equipment in my house supports it to be able to really take advantage of it seems like it might take a while. I'm actively trying to purge old technology, but that still seems like a few years away for me.