Also, paging @steve dave: is there a way I can use some of my leftover Lufty miles for a United flight without calling someone up on the phone (gross)? I'm looking to get rid of them. Can I just transfer them to United or do I have to book through Lufty?
you will have to call
Go to United.com and enter your travel information.
Don’t forget to check the button for “Award Travel“
Write Down the Flight Information
You are searching for “Saver” or low-level awards in the cabin
They will show up as a blue button under the left column for economy, center (or right if there is no First Class) for Business Class, and the right column for First Class.
Write down the flight information for the flight. Call the Lufthansa (NOT United) service center and ask them to book that award for you.