Since you're planning on getting into relaoding, you'll need a sturdy bench to mount your press, powder measure to. Make it big enough to (at least temporarily) hold a gun cleaning cradle and possibly a vise. Above the bench I'd also put a lot of shelves for powder, bullets, dies, etc. And run a power strip along back of it for the electrical gizmos you're likely to use one day (case tumbler, case prep station, scale, etc.) A framed in closet to hang your clothes would be nice too. Make it as large as you can. The only regret over the 16x24' shop I built is that's it's not TWICE as big as it is.