Dad's dad's dad's family was largely German.
Dad's dad's mom's family was from the South since forever (at latest the late 1700s), so probably mostly Scotch-Irish.
Dad's mom's family was from the Mid-Atlantic/Northeast since forever (some since the mid-1600s), so some combination of English, French Huguenot, Dutch, Scottish, Irish, German, and all that jazz.
Mom's dad's family was largely Irish Catholic, including some from County Waterford.
Mom's mom's family was largely Northern Irish Presbyterian, though they lived close to the border and some were from what's now Ireland.
It was a great family scandal when my mom's dad married my mom's mom.
I'm on 23andMe and have both my parents involved, so I can also give estimates based on that. 23andMe estimates that my dad has ancestry in about this order:
1. UK
2. Germany
3. Ireland
4. Norway
5. Italy
6. Sweden
7. Poland
8. the Netherlands
My mom, meanwhile, has:
1. UK
2. Ireland
3. Sweden
4. Spain
5. Poland
6. Norway
7. France
Note that the UK and Ireland nearly swamp out all the rest of everything, while my dad's ancestry is much more diffusely arranged, in line with the fact that my mom's ancestors are much more recently in the US than my dad's. There are also a variety of other considerations at play here, but I won't go into them too much
