In terms of switching - bit of feel - bit of look - make sure you can't see any grooves in the wood you didn't create - the basswood bodies I've worked on tend to have a lot of tool marks around the body. These can take some work to get them out but will come out with time. Once you think it's done, get a damp rag and run it over the body against the grain - that will make any "fluff" stand up and you can knock that on the head as well. By the time you get to the higher grits (240+) it's more a once over to clean up any sanding marks that you have created. Don't go too far over 240, depending on wood as you'll start to polish the wood and it'll reject stain.
With spraying I'm not sure you need to go that hard with sanding as you will be using a sealing spray that will even out a lot of the imperfections. I'd still get rid of tool marks / dings / etc, but in terms of going beyond 180 odd - not so sure (that said - never sprayed a guitar).