Some people know this, others don't but the true secret to a good sounding board is the "AMP". I don't care if you have a Motif, Trton or Fantom, pipe it through a sorry amp and see how it sounds. 
But on the flip side, if you take a Casio and pipe it through a good amp, it can do wonders.
Tell'em one more time Bossman!!! When you go to guitar center, or Sam Ash, or wherever it is you go, they got those boards hooked up to studio quality monitors or high quality amps. Don't get me wrong, the boards yall are talking about are nice, but you could take a less expensive board and pipe it through a High quality monitor or amp and you would be surprised at what you hear.
I agree that whoever does the casio line, needs to fire the industrial designer who did the packaging ( but maybe it really does make a difference in the cost). But the Privia and Wk Series don't sound bad, they just don't have a lot of options.
But like the Boss ( 4HG) said. figure ot how much you can spend first. You will be out there playing on a Fantom S/X and then the church says you got to do it for a thousand or less, then that triton le just doesn't sound as good anymore.

My personal preference is Roland by the way. If you primarily need a digital piano, weighted keys, with good organs, ep's, horns, and piano sounds, then the rd700 s/x is the way to go.
i encourage anyone who is ever thinking about playing piano, to buy a board with weighted keys ( if you can't afford or place a real piano in your music room).
Jlewis