WHAT'S THE DEAL WITH WATTS?

I'm considering acquiring a new (for me) integrated, under $2k, to drive my KEF full range speakers. They are very efficient (93db) , 4ohm and rated for 50 - 200 watts.  It seems that a good amp with 80 or 100 watts per channel at 8 ohms will take these speakers to any volume I'd want to experience in my medium sized living room.  So what advantage/benefit in sound am I going to get with 150 -200 watts, or more, per channel? Is it worth spending more for extra power that will never really be demanded?