Looking for a Trail Bike

Your level of experience with cycling

I'm fairly new to mountain biking but want to get a lot more serious.

What's your price range, and have you considered second hand?

Currently want to spend max of $1000 definitely wouldn't mind second hand though.

What's your intention with the bike - commuting, fitness, touring, sport, etc?

My main intention is to go trail riding in my local area (Lebanon Hills, MN) and maybe taking it out occasionally to Colorado.

How far will you be riding, and how often?

I'll probably ride it an average of 15 miles each time I go about once or twice a week.

Riding conditions: roads, pavement, trails, single-track, off-road? Flat or hilly? Traffic and weather.

Mostly trails, lots of rocky terrain, and hopefully something that will work well for more advance terrain as I continue to advance.

Your location (even approximate) can help other locals familiar with your conditions, too.

Live in MN and visit CO frequently.

Additional:

I have done a couple of demo's at Lebanon and typically always favored the Giant bicycles. I have no recollection of what models they were anymore unfortunately. I'm looking for any recommendations. I'm a 20 year old male, 5'10" and weigh about 170lbs. If that helps in recommendations.

I appreciate any and all input. Thanks!