I live in Canada and now that summer's is getting closer I've decided I was going to bike to work all summer. The only thing is I don't know the first thing about bikes and I would really appreciate some advice on what's better. I'm going to be doing a total of 30 km a day or 18.5 miles.

I went out to different bike shops to look at hybrids and I've narrowed it down to 4 bikes in my price range:
Diamondback Miramar - $350
Diamondback Kalamar - $400
Miele Toscana 100 - $330
Kona Dew - $400

I've tried finding specs online for these bikes but couldn't find anything except for the Kona Dew. I do have brochures with the specs for the other bikes and I could probably scan them and post them as images.

Thanks to anyone that takes the time to give their opinion.