ok... so you are wanting to power XX or YY new speakers from the New pioneer HU?
IF so... you need to look at speakers with a sensitivity of 90db and higher... the higher the db the better. Alpine's S-series components and coaxes are in the 90-92db range and are specifically designed for running off HU power. Above all do NOT buy anything Infinity to run off HU power. They are horrible in the midbass range off even a moderate amp power, let alone whimpy HU power.
Like when buying a head unit. You gotta take your music, in the format you will listen most (ipod/MP3, CDr, whatever) and listen to speakers that make YOU happy. Ignore the jackass with the name tag telling you what to hear. Yeah, that's me... Im the jack ass... LOL. I've been doing this long enough i try to let my customers listen for themselves and only answer questions, not tell them what to hear.
After you find a BRAND who's sonic signature makes your ears happy, then start shopping online for the different levels inside that brand's line. figure out what you are comfy spending and then TRY to find a local dealer, TRY to haggle, but bottom line is $$ talks.