Having no big hills on my commute means I can go at a fairly fast, consistent speed, which is why I chose this slightly more challenging gear combination. I don't need any low gears for steep climbs, and I don't miss the tall gears either, because there's no roaring down big declines, trying to keep my pedal speed up to keep pushing the bike forward.
I can't claim any brillant analysis that caused me to go with this selection. Basically the great people at my local bike shop went in the back, rooted around for a while and came out with these parts and said "try these."
I would highly recommend working with a mechanic from your LBS who knows what they are doing to get these components, cranks, chainring and sprockets, if you try a similar project. They'll likely have many of the components right there on hand and you can try them out on the spot, swapping out for another if they don't fit right. Plus, bike shops often have boxes of like-new components that they will give you for things like this for a song. It's definitely easier than the time and expense and guesswork involved with ordering online. You send off for something and two weeks later in comes in, only to find out that it doesn't fit and you have to send it back. Ugh.
I have found that bike shop people love projects like this too and will often get as excited about it as you. And if you bust out a six-pack of beer on them afterward or some other similar token of your appreciation, you'll have a friend for life.