Stumped on a middle name

My husband and I are having boy/girl twins in March and are struggling to come up with a middle name for our son.

Our 22 month old daughter’s name is Mila Sophia, and our plan is to name our second daughter, Penelope Parker. We have settled on the first name Maddox for our son, but we cannot seem to come up with a timeless middle name. Do any of you mammas have suggestions?!