There's a lot of options these days.
You can get a hardtail with just front suspension for a lot less than a comparable full susp. bike.
Suspension travel varies from a couple of inches to 8+. For recreational trail riding 4 front and rear should be good and that's pretty standard on XC bikes.
The major companies would be a good starting point since you can get the most bang for the buck on a budget. Out of those I'd recommend Giant, Specialized, and Trek. I've ridden multiple bikes by all of those companies. If you wanted to look into boutique brands, let me know and I can give you more info. You'd be spending more, but generally get higher quality, handbuilt, and better components (of course, components can always be upgraded). Also, check out craigslist you can often find good used deals on some higher end stuff.
This is what I ride:
Downhill (8/8): Giant Faith
Trail (6/6): Rocky Mountain Slayer SXC70
Freeride Hardtail (4): Norco Sasquatch
Road: Giant TCR2
BMX: S&M Dirt Bike Classic
Pics of my mountain bikes:

The Faith

The Sasquatch and Slayer
Also, if anybody is interested here is a video I made a few months ago of me and some friends riding last year:
http://www.vimeo.com/2501696