I also work at a bike shop--a Fuji and Diamondback cycle shop in Tallahassee.
I have to say that one of the most demanded types of bikes are hybrids. They are great for those who aren't going to get heavily into cycling. Their tires are also better for use on pavement and streets--the thinner, more road-bike style tires prevent wear and help with speed.
Personally, I recommend the Diamondback Edgewood. It's an average bike/average price, but not a hybrid that looks like a beach cruiser (as many do, with fenders and wide handlebars.) But, if you're into that, then the Fuji Crosstown 3.0 is the way to go.
But, nothing's wrong with a lower end mountain bike (assuming you're not going to get into anything off road that's too difficult.) There's a bonus side of being able to take them on trails in parks near by if you get bored of riding the same old route. Plus, they're very hardy.
I recommend the Diamondback Peak or Response.
They have very good Shimano components and hold up well on normal trails.
Remember, when you're sizing a bike:
When you're standing over the frame, on a mountain bike there should be around 2-3 inches between you and the top tube.
On a hybrid, there should be around 1.5-2.
Size is critical. Do no settle for the wrong size, or you could end up with wrist, lower back, or shoulder pain.
I am 5'6" and I use a 19" frame mountain bike. That should give you an idea for a comparison.