I just recently set up my old Apple IIGS again. I was pleasantly surprised that the old 270 MB SCSI hard drive still works, although I’m backing it up to a 1 GB SD card as I type this. (I got the SCSI2SD (v5.1) so I can use an SD card as a hard drive.)
The AppleColor RGB Monitor also still works (these old CRTs often don’t) but I’m looking forward to the release of the VidHD card so I can get an HDMI port and use a proper 1080p LCD. 
The clock battery was dead, but thankfully it hadn’t leaked so I just pulled it out and I ordered a new one off Amazon.
I’m using a FloppyEmu in place of floppy disks, but at some point I should work on getting the original 3.5" and 5.25" drives working again. (The eject mechanism in the 3.5" drive needs a gear replaced and the 5.25" drive needs its speed adjusted.)
While I still have some working ADB mice and keyboards, input devices have come a long way in the last 30 years. So I use a ADB-USB Wombat to hook up a modern keyboard and mouse. Ok, so if I still had my Apple Extended Keyboard II then I might use it, but I don’t, and pretty much any USB keyboard is better than the few ADB keyboards I still have. And as far as I know nobody ever made a decent ADB mouse. 
So far the original power supply is working fine, but I may need to replace some capacitors at some point. And perhaps replace the power supply entirely with a beefier one; with a 10 MHz ZipGSX and an Apple II High-Speed SCSI card and the VidHD card (once it’s released) I may end up pushing that power supply harder than it can handle.
Anyway, I need to use my Glowforge to make proper enclosures for the Wombat and the SCSI2SD. The FloppyEmu came with a nice laser-cut acrylic case but I might also make a new one for that, too.