I just added an old floppy drive to my desktop PC. Looks a bit strange, shiny black case with a faded beige floppy, but it has a wee door on the front so you don't notice most of the time
I use HFVExplorer and VMac to get files onto floppies.
Anything I want onto the Mac Plus, I have a few 800k disks, I use the classic as a go-between swapping the 1.44MB floppy and the 800k Plus floppy.
Long term, I am looking at a SCSI ZIP drive. This could be the HDD for the plus, an external drive for the classic, and I have a Parallel (really a SCSI without the SCSI chip...) ZIP drive that I can connect up to the PC to download anything I fancy.
You could ethernet them, but I tend to think of compact macs more as standalone machines, good for games, recipes DB and word processing (the keyboards on both are a joy to type on!)