Shelving. Lots and lots of adjustable shelves that can change with your inventory. Also try attaching keyboard trays under your work surfaces so projects can slide out of the way but still be accessible.
Look at kitchen displays in home-improvement stores for ideas on customizing your space - some of the cabinets are pretty inexpensive and can be "upgraded" with things like slide-out drawers and tip-outs.
How nice to have all that space! You're going to have a ton of fun getting everything the way you want it!