I can't always do a terminal shutdown. Seems like the SD Card is caching its "writes" or something. Any suggestions??
The OS caches writes. Always has. You need to cleanly shutdown filesystems when shutting down, which means you have to do a clean shutdown, not a reset.
You could set up an action in udev so that when you attach a particular USB device the system reboots. You'd just need to make sure it's not something you want to actually use on the system, and to remove it as soon as the shutdown is underway to prevent a reboot loop.