My FI and I are sending out our Save the Dates next month - wooo!

We have them designed and I am working on address labels. Curious though, how do I put the return address. We live together.
Should it be:
FI Last Name/My Last Name
Address
City, State, Zip
or
FI & My Name + Married last name
Address
City, State, Zip
or
just address to one of us?
Any input is appreciated!