the problem with shopping only at local bike stores is that they will go out of their way to recommend that you buy only whatever they have in stock. for all the praises sung of the LBS, I must report that I have been underwhelmed by the disingenuous and even downright dishonest approach of many stores I've been to.
A crappy LBS will do this, but not a great one.
I've found the bigger problem at many shops is that they consider a trek 1500 with low spoke count wheels and 21mm tires to be a nice "commuter bike".
For commuting look for something with fenders, a rack, larger tires, maybe even a chain guard. For $800 you can get an extremely nice internal geared bike like a Jamis Villager or Uptown, which are great commuters.
It just depends upon how you intend to ride. If you want a bike that you can ride to work but also ride in roadie group-rides occasionally, you may want to look at road bikes. I personally like touring bikes, cyclocross bikes, and actual "commuter" bikes for my riding.