Can Screen Contrast Be Adjusted?

There are no contrast adjustments as far as I'm aware.

My wife's Xenon (my old Xenon) is a little flakey - the screen brightness is overdriven, but if I wiggle the display sometimes it goes back to normal.  Have a spare phone waiting in the wings in case it wigs out though.

Sounds like your problem is similar to the problem on my wife's phone.

I highly recommend the following to keep your data accessible in the event the screen completely goes out:
1. Set Save To location for everything possible to Memory card.  If you don't have a MicroSD card, it would be a good investment.  This will save pictures, videos, and music to the memory card, at least.  Ringtones and purchased content will likely not move.  Applications can be moved to the memory card, but it doesn't help much for recovery.
2. If you don't have a Micro USB cable to connect the phone to your computer, get one.
3. Set the USB Connection Mode to Mass Storage so you can read off the card.  If you have a different way to read Micro SD cards on your computer, or if LG PC Suite II works properly with your phone, set the USB Connection Mode to Data Service so you have some access to the modem and phone interface.
4. Back up your Contacts to SIM card, or if LG PC Suite II works properly with your phone, back it up with that.