im wondering which two lenses should i get for when its sunny and flat light conditions???

I rock the gold mirror sol-x (7% VLT) on the super bluebird days here in AZ, it's like alpine-glow all day long. Cuts glare like nobody's business...

Ignitor or Platinum mirror lenses plus Sensor mirror would work well. The VLT in the ratings stands for Visible Light Transmission, or how much of the light around you the lens lets in. High numbers are good for dimmer days (more light means you can see more) and low numbers are good for bright days (less light means you don't blind yourself). I ride with either the Platinum or Sensor lenses in my Fuses pretty much all winter, and I'm a fan of both, although I'm thinking about replacing the Platinum with an Ignitor now that they're getting scratched. Either way, both the Platinum/Sensor and Ignitor/Sensor combinations should cover you on anything from bluebird to pea soup (if you do any real amount of night riding, pick up a clear lens from Smith too).

would platinum mirror and sensor mirror be a good idea cos platinum lets only 25% light through and sensor lets 70%????

I have the Sensor and Ignitor Mirrors with my Smith I/O's, and they pretty much cover all conditions I see where I am. Ignitor for pretty much anything (35% VLT) and Sensor for the bright days (70% VLT)