That's basically my setup.  The Polk's IMO are a better system.  The towers alone probably weigh twice what the Athena's do (at least they feel like it).  The Athena's handle power much better, and you don't need a powerhouse of one to power them like the RTi's.  Dollar for dollar, everything being the same, go with the Polks.  If you can get the Athena's for a lot less, go with them.  Depends on your receiver.  Any good SV Subwoofer will do with either system as long as you have the room for it.  Figure $500 for an SVS.