For interplanetary travel (not interstellar, just between planets in our own solar system), I'm not sure a shield would be strictly necessary.

Also, what is a sphereship but several layers of disk-shaped "floors" of varying diameters? I suspect that the proper next step from a diskship would be a tubeship.

Maybe edge-on is a better way to do it, though. I hadn't given much thought to the proximity of engines to crew quarters.

However, I do imagine a series of concentric rings. The central core would be a kind of CSM stack, with an engine at the bottom and a flight deck/storm cellar at the top. Wrapped around the central core would be the fuel and air tanks. Wrapped around that inner ring of bulk consumables would be the electronics and storage cabinet rings. The outer ring would contain shirtsleeve environments: living spaces, observatories and labs, with the maximum useful gravity the spin can impart.

Perhaps the whole thing could be constructed skeletally, like a spiderweb, with the spaces filled in with inflatable hab modules or hardshell storage tanks and cabinets. Tough, flexible ribbed tubes acting as airtight gangways between central core and outer ring and all the storage spaces in between.

Thank you for your thoughtful responses.