I am wanting to get into riding some basic trails and am looking at an entry level MTB. I rode the Trek 820 and 3500, as well as the Giant Revel 2 along with several of the more expensive bikes. I seem to like the Trek 820 and the Giant the best. The Trek is cheaper and comes with free adjustments at the LBS. Any recommendations would be appreciated. I am in the $300 to $400 dollar range so I know that limits my options. Just trying to get the best bang for the buck.

Thanks

The Trek 820 upside, very versitile, overall rugged bike that can take a lot of punishment and keep on going. It can be used on trails, including technical stuff. It's also a good all around bike for commuting, riding on streets, rail to trails/MUPS etc. The steel frame helps to absorb shock.
Downside, it's a heavy bike, a little clumsy on difficult trails. The frame is a dated design (almost identical to the 2001 model, the year this frame came out), The 3500 has a more up to date design.
We own a Trek 820 and it's a good overall bike but can't hope to compete with something like a Trek 4300 or a Specialized Hard Rock.
Can't comment on the Giant as we've not had that model in our group of bikes.

I think either bike would be fine for you, you aren't going to go wrong with either one.