Plans are loosely based on the Black & Decker Basic Shed and the Casita House (.pdf link) from Baja Christian Ministries. The Black & Decker Basic Shed meets all building requirements, but in one respect, its overkill for my needs. The shed will be positioned on a concrete slab, but on a "skid" so it qualifies as a shed and not a building (avoiding the need for permits and inspections). The Casita House has both a cheaper flooring plan using 2 x 4's that I'm using -- since the load is transferred directly to the huge slab, I don't need 4 x 6 runners and 2 x 6 floor joists. The Casita House also has an alternate low-profile roof line that I might use (but probably not).
Like the Basic Shed, my shed will be 8 x 12, but with double doors (5' opening) along the long side. A single door will be provided on one of the short sides to help with lumber storage (don't tell my wife). Yard equipment as well as Christmas decorations, etc. will be stored in the shed.
I'm making the rounds of the Habitat for Humanity ReStore salvage shops this week to find the doors and any windows I could use ... ReStore has a ton of very cheap building materials donated to them, and Habitat clears enough from each store to build an additional 10 - 12 houses each year.
B&D Basic Shed: