Thanks for the reply justabuhler. I'll be mostly biking in the city, through parks and on the road. Some uneven terrain, but mostly pavement, gravel and grass. I am not expecting to do any winter biking. I would like to use the bike to run all my errands and for family outings (library, park, etc) within the city to replace the use of the car. I am 5'6" tall. The person at the store said I would be a "medium" (just from looking at me). I am not an experienced biker, in fact I am not currently biking at all. We walk for most errands, but biking would be faster and expand our available area.
Perfect, so you're just gonna need a good all around bike, a medium frame is correct, a 26" tire will be fine. Both Specialized and Giant are great brands, and what really sets the bikes apart these days are just the different components each bike has.
While our big box retailers sell bikes in large numbers, and cheaply, the componentry on them is horrible, and the craftsmanship is also not there, and the customer service should you encounter an issue or try to even attempt a warranty claim is well, not gonna happen.
Buying used is always ideal, I by most of my bike parts on clearance or second hand from a biking website called Pinkbike.
http://www.pinkbike.com/buysell/You can search for all the listings in your area for XC / All mountain bikes there, and sort them from cheapest to lowest $500 should get you a great used bike.
If you are looking for new options, I'm a big fan of Norco, Rocky Mountain, and Brodie (great canadian companies).
http://www.norco.com/bikes/city/lifestyle/http://www.bikes.com/en/bikes/metro/2014#/models/metro-10http://www.brodiebikes.com/2014/bikes/voltage.phpIf you have any questions, please ask away.