I have the annoying problem with 12.10 that it lists the extended partition containing my SWAP in nautilus (labeled "Ubuntu 12.10 i386"), so I want to open up disks to check off the 'Show in User Interface' option, only it's grey'd out. Is there a way to open Disks as sudo so i can check off that option?
You do not need to run Disks as root to do this. To set your own mount options for a volume, you need to turn off Automatic Mount Options. This is done with the switch at the top of the Mount Options dialog. Just toggle that switch so it says "Off" and you will be able to change the mount options as you see fit. When you click OK, you will need to enter your password for the changes to be applied.
With "Automatic Mount Options", volumes are mounted as they appear. When you turn that off, Disks adds an entry to /etc/fstab so the system always knows to mount that disk at startup, and in a particular way. I'm guessing this partition contains a swap file or something of the sort, so you may want to change the Mount Point field or reconfigure your swap file, since the mount point will be different from when it was automatic.