Since space is an issue in your sewing room, I would consider perhaps a Janome 8900 which has a big enough harp to make machine quilting easier but also has an assortment of decorative stitches. Unlike some other Janome models, it has a free arm that makes it useful for garment sewing as well as quilting.
A lot of people really like the Brother DreamWeaver machine, although I think there is an even newer model out with more features. This is another all-singing all-dancing machine.
Edit: Limited space is definitely an issue. If you had more space, I might recommend a combination of several machines, each engineered to deliver the highest quality specialty applications. For example, I might recommend a Juki 2010 for piecing, a Sweet Sixteen for machine quilting, a Brother PE770 for emboirdery, and yet another machine for decorative stitches. And perhaps a high-end serger for both garment sewing and decorative stitching on quilts.
