Commuting - Help! It's down to these 2 bikes!

http://www.diamondback.com/bikes/performance-hybrid/2010-performance-hybrid/insight-1-10/

http://www.marinbikes.com/2010/bike_specs.php?serialnum=199

I'm having serious trouble deciding which bike I should be choosing. They're both priced at the same price point, I'm a total bike noob, but looking at the specifications, they both seem very similar...
The tires on the Insight appear slightly bigger (will that let me bike faster?) but that could be just the image...I really need your help bikeforumees! :(
I'll be using it to commute from work on road/pavement 12mi/20km round trip on the weekdays!

I would think the Marin. You should really learn a little about geometry and fit. That'll make the biggest difference. Neither bike seems to be impressively spec'd but they are not very expensive, either. Could you save a little more money and spring for something better? Also, why did you want a hybrid? How do you intend to use it? Flat bars are sort of iffy for longer rides.

I would think the Marin. You should really learn a little about geometry and fit. That'll make the biggest difference. Neither bike seems to be impressively spec'd but they are not very expensive, either. Could you save a little more money and spring for something better? Also, why did you want a hybrid? How do you intend to use it? Flat bars are sort of iffy for longer rides.

Between them both the Marin has better geometry, but neither have good geometry??
I am hesistant on spending too much because I'm worried an expensive bike will attract attention and get stolen since I will be locking it outdoors. I need a bike that is quick and nimble since I will be riding it every single weekday if weather permits.

I chose a bike with a flat handlebar because I assumed the ones with the curved handlebars will attract attention and are only for pros/roadbike racer cyclists.

Agree with the Marin, but if for no other reason than it has puncture-resistant tires, which are useful.

I disagree with the above comment about flat bars and long rides. Though a singular hand position certainly has the potential to cause discomfort over long rides... 1) 6 miles 1-way is probably not long enough to do you any harm at all, 2) 'fit' makes a bigger difference than multiple hand position options, 3) you can have just the same pain or nerve compression problems with multiple positions.

Also it looks like that Marin has mounts for a front low rider rack. While I doubt you'd ever use that from how you describe yourself, I think it's a thoughtful bit of design on Marin's part, and cool to have the option.

Get the Marin. I have not had good luck with my Diamondback (although granted it is not the same model) at all. No fender mounts (well, it has them, but no realistic way to mount them), crap shifting gear, and above all for the price you can buy much nicer (like the Marin).

I don't know what your budget is, but Marin has their line of ALP bikes. The low end is MSRP $590, the Belvedere. I have a Mill Valley, which is a great bike. They are flat bar road bikes, but made to ride faster than a typical hybrid. Thinner tires, etc. I really like it.

I disagree with the above comment about flat bars and long rides. Though a singular hand position certainly has the potential to cause discomfort over long rides... 1) 6 miles 1-way is probably not long enough to do you any harm at all, 2) 'fit' makes a bigger difference than multiple hand position options, 3) you can have just the same pain or nerve compression problems with multiple positions.

Agree with these comments. A flat-bar hybrid style bike works for this short commute. And the most important thing is how the two bikes feel when you ride them, is the fit good? Assuming you can test ride both bikes, take them out and see which one you like riding better and is the best fit for you. They are both similarly spec'd and priced, so it should come down to fit.

As long as it fits you, I'd go with the Marin also.