MY advice is try all the local stores and both pick the store most helpful as noted above and the bike that seems to fit best. One warning and that is many LBS try to sell a bike they have in stock, even though it doesn't fit rather than order one.

As far as hybrid vs cyclocross, it's more about your long range goals (cyclocross is better for longer distances and going quicker) and your overall level of fitness and flexibility (hybrids are an upright sitting position). You really are wrong about cyclocross is a "purpose built race bike for relatively short rides on a specific type of race course." True they are raced but they are really a road bike with wide knobby tires and mountain bike style brakes. Many people use they as commuters or an all around single bike. It really depends upon how far you plan on riding on your typical rides and how comfortable you are on either.

Good luck.