I believe shwinn was bought by a 'big store' and is no longer a good mtb. I remember hearing that. I would go with specialized, norco, or Giant. I would include Kona in there but they may not be in your area.

You will need steel. If you are planning on using it hard I can tell you right now you will be replacing rear wheelset (on any standard bike),freehub every few months, bb (standard ones suck in the under 1000$ class), pedals and maybe crank arms. Bikes dont keep working they take loving and at your size (I am 6'5 and 250) they need a lot of loving.

Next, try a few out there are different geometries for diffrent styles. xc or freeride. Go to a local bike shop and try a couple out. Rent each for a day and play around. When you figure out the basic gerometry then we can discuss bikes.