Since I somewhat know the family migration patterns, I don't do many global searches. Most of the time, though, I have been able to locate a marriage record that provides the wife's maiden name.
My research covers mostly Massachusetts (outside of Boston), New Hampshire and Vermont, perhaps a 30 towns between them.
In the case of one New Hampshire town, we couldn't find the maiden name in the vital record book, but based on my phone call, the town clerk found the maiden name have been recorded in what was the earlier town clerks' book.
Depending on the date of your "voids," and whether or not any of the children settled at Massachusetts, know that those the Massacusetts marriage and death records post 1845/50 often/generally report the mothers name; I believe where she was born, too. Some of the other locations follow suit, but for me that is still later and/or spotty.
I have found that while all the record indexing is fairly good, there are some variations between what I find in these vital record collections at FamilySearch, American Ancestors, Ancestry.com, etc. (There is also a separate site with Massachusetts town records.) This means that if I find a negative search on the index of one set, I will generally check the collection on another site.
Scholarly journals. You likely have searched The Register. Depending on how the families migrated, you may want to research the New Hampshire Genealogical Record.
Court records. My success with these records has mostly involved Essex County, Massachusetts.
Last but not least, local or archival libraries. Particularly in New Hampshire and Vermont, I have located exceptional records/notes in family files.