Sounds like you want a bike for commuting and general riding on pavement. My choice would be a road bike. A cyclocross bike is a reasonable choice, but the disk brakes are unnecessary (esp in AZ). The Scattante looks okay. The Gravity looks terrible. I would not convert your existing bike. The 29'er conversion makes no sense (way too heavy, wrong geometry, suspension on the street is bad, expensive because you'll need new wheels and tire too).
Make sure you get
- correctly sized bike! Very important. Educate yourself - don't assume a bike shop will put you on the correct size.
- reasonably sized tires: 35mm is unnecessarily wide, for street 25-32mm is ideal. Bigger = heavier.
- rack mounts: for panniers if you commute with stuff
- when saddle is the correct height for you, you should be able to lower the bars so the tops are equal to or a couple inches lower than the saddle. Via moving spacers and a different stem.
- no suspension! Heavy and inefficient. A big frost heave is not a reason to have suspension, you just get your butt off the saddle. Suspension is for off road.
- all else equal, lighter is better.
Given your price range, you can look at other brands too.
If you're willing to buy used, you can get a road bike far better quality than the options you named, for less money.
Last edited by jyl; 02-16-14 at 08:26 AM.