Academic Search Premier: an excellent database to rummage around in after you've sampled what articles are available -- or seem to be surfacing first -- in a HOLLIS "everything" search.
Academic Search Premier is also multidisciplinary in its coverage and also provides you with a range of article types (some scholarly, some not). It draws its information mainly from journals, though you may find book reviews, the occasional dissertation, and magazine and news articles in your results list.
But while still broad, it's a smaller universe than HOLLIS, and depending on your topic, searching in ASP may seem more manageable.
Familiar and current, it also searches full-text, which makes it different from the other databases (including HOLLIS) on this guide.
Full-text searching can be an advantage when you've got a very narrow topic or are seeking a "nugget" that traditional database searching can't surface easily.
Google Scholar is perfectly acceptable for most general forays into scholarship; its algorithms are excellent and do return relevant results.
NOTE: One simple change can turn Google Scholar into what's effectively a Harvard database -- with links to the full-text of articles that the library can provide. Here's what to do: