I was in the same boat as to where to go next.
My solution (based on thinking about immigration in the news and a memorable trip to Ellis Island with extended family) is to identify and target my research on all my immigrant ancestors and their immediate families.
I had read on g2g that most people know the names of their immigrant ancestors but tend to hit a brick wall with finding records back home. I have found this to be true.
I am listing every direct ancestor who made an immigration journey in a spreadsheet, as well as whether I know their parents' names, whether there are sources, whether their profiles have a list of their kids, and how many of those kids have profiles. I have a few other columns such as approximate date of immigration, do I know the ship name, where did they immigrate from and to, do they fall under a project like PGM, New Sweden, New Netherland, etc. On a separate tab, I have all my U.S. brick wall ancestors listed. Having a sortable list of these locations has made it much easier when I have only one day at an historical society to blitz research everyone I can.
I just finished going back on my grandmother's side and know the names of 61 of her immigrant ancestors. If you're curious about this method, PM me for a link to the spreadsheet. Happy trails to you.