What kind of power supply would you guys recommend for two gtx 660's in sli that are not overclocked?
Either one should work out fine and if you want to upgrade in the future you have headroom to do so
http://www.amazon.com/dp/B009YC3EAI/?tag=pcpapi-20
http://www.amazon.com/Corsair-Enthusiast-Watt-Bronze-TX750/dp/B004MYFODI/ref=sr_1_5?s=electronics&ie=UTF8&qid=1396919489&sr=1-5&keywords=750+watt+power+supply
700W and up will be plenty. I'd go for a high quality PSU.
The RM series from Corsair is very good and very quiet.