without spending $1000's on purpose built studio furniture - Ikea's
Galant is a cheap, customizable solution.
I added a monitor shelf, which would hold 3, and allows room for 6 rackmounts below. There is plenty of desk space (63" x 32") and is expandable to allow for an L shape addition, or straight extension which might provide for desktop synths.
Add a keyboard tray, or midi keyboard pullout and your looking at ~$300 (78" length).
Heres a quick snap of mine