DO NOT BASE YOUR DECISIONS ON THE RANKINGS THEY ARE COMPETELY IRRELEVANT THEY ARE DISAPPORVED BY THE ABA, LSAC, and AALS and each organization specifically denies their validity.
The Association of American Law Schools has also voiced complaints; their executive director Carl Monk went so far as to say "these rankings are a misleading and deceptive, profit-generating commercial enterprise that compromises U.S. News and World Report's journalistic integrity."
The U.S. News rankings are not approved by anybody and their rankings are literally based on nothing. The fact that you saw the schools you are considering drop and change so much just shows how unreliabile they are. Whatever school you end up going to could be tier 4 or tier 2 the next year. Obviously, Harvard, Stanford, Yale etc are great schools, but nobody really cares outside of the elite schools and tier 2, tier 3, tier 4 are all regional.
Go to law school in the city you want to live in. Take scholarship money if you can, but if there is a drastic difference in the rankings then you can take them into account. Hastings is a better school than GGU there is no question as to that. However, GGU Santa Clara, USF they are pretty much equal in the Bay and the difference in the rankings outside of the bay is completley irrelevant, because they are all local schools.
I almost made a decision based on the rankings last year and it would have been the worst decision of my life. So just to warn you before you make a big mistake relying on the rankings. Use your common sense it has a lot more merit than U.S. news does.