Gingrich is interesting because it's possible he helps neutralize one of Clinton's big advantages, which is nostalgia for the success and stability of the '90s. Trump and Gingrich can just attribute the prosperity to the Republicans in Congress and argue that their ticket now has the winning recipe.
Problem is, it's Newt Gingrich.
If Bob Dole weren't so old, he wouldn't have been a bad pick.
If it is a Dole, it will probably be Liz Dole. She is 13 years younger, female, legislative experience, and from a critical state.