Right now I'm leaning towards two powered 12" two-way mains and one or two 15" or 18" subs. Just not sure how available good powered speakers are.
Just out of curiosity, why are you looking at powered? You may find that the "personality" (dynamics, EQ, crossover/drive/port distortions when pushed, how your power amp goes into clipping or limiting - I could go on...) you enjoyed as a DJ will not be accessible with the canned processing in any reasonably priced powered speaker. These sonic traits will be neutered.
In other words, if you want control over, to be able to use, these "bad" things to create your signature sound, then you will be disappointed with budget powered tops. Powered subs are similar, but less so. Try using a Kosmos-type LF generator to liven up old recordings that had no real bass, and you will find that the powered sub's built in DSP will filter out most of it.
It is not about sonic accuracy; it's what
do you want
it to sound like.
I recommend borrowing an Sx300, as they can be had for cheap at *rhymes with cheesy* in nearly new condition. You will hear an abundance of clarity (you referred to it as "bright") and pretty satisfying bass. This is as close to a "full-range cabinet" as I've experienced at this level (my level, my opinion, of course). Add sub to taste. Be prepared, as the Sx300 will easily keep up with a dual 18".
-Dennis