The Marin Rift Zone 29er XC6 has disappeared from the Marin Web site — but you can find it at REI. And I am sure you can get it configured via the Web site or your local pro-shop. Check it out. This bike combines the big wheels of a 29er with the comfy ride of a full suspension bike.
The material for the frame is aluminum. I could not find reference to the weight of the bike but as most 29ers go expect on the heavier side.