I went the opposite direction. MTBing to roadie world. I enjoy them both, but MTBing is my first love and IMO the most enjoyable.

I personally like the REI Stores. Corporately they volunteer tons of hours building trails and setting up mechanics stops on local charity rides. They also have good bikes. PLUS, if you travel with your bike, you can get service at any of their shops.

For your price range I would look at a Scott Spark (Full Suspension) or Scale (Hardtail)

This Spark is a closeout from 2013, setup well and has 650B tires. This way you can be innovative and controversial.

http://www.rei.com/product/842566/sc...-650-bike-2013