Upgrade from ASUS DSL-N66U?

Hi There,

I'm about to have fibre installed (been waiting seven years, I only live in Sandringham(centralish Auckland)!) and I'm considering an upgraded router.

I currently have an ASUS DSL-N66U which is located centrally in our house, and I find the WIFI coverage patchy on the extremities of our house - e.g. in the study or bedrooms.

Is there an all in one router out there that will provide better WIFI coverage than what I've already got? Is there another option that I haven't considered?

Thanks in advance for your responses.

Dave