Bike Habitat is indeed a great bike shop. I got both of my bikes there and I was an absolutely beginner when I purchased my first bike. But it's important that the bike shop be convenient so check out other options convenient to your home or workplace. In addition, typically bike shops only carry a few brands and at this point you don't need to narrow yourself down to a particular brand. It would be great if you can visit a bike shop during an off-time (i.e., not on a weekend) so the staff can easily spend a bit more time with you.
I'd definitely encourage you to bring your girlfriend in on the plan as bike fit and preferences are individual and somewhat unpredictable (e.g., some women like "women-specific design" bikes and others don't). If you want it to be a surprise, perhaps you could give her some sort of a bike icon to indicate the gift such as a bike tree ornament or something offbeat like a bike lock?
If you are thinking of hybrids (flat bar), you might try the Trek FX line (and Bike Habitat carries Trek). The line ranges from approx $450 - $2,600 and might give you a good sense of what you can get at various price points.
You might be surprised at much you ride. I purchased my first bike never imagining that I would do a ride of more than 40 miles in my life. Fortunately, my first bike allowed me to do much more.
Good luck!
2003 Trek 7500FX/standard saddle
2006 Trek Pilot 2.1/Serfas cutout saddle