Man Utd need a lot of changes but they have several good players (Van Persie, Rooney, Mata, Kagawa, De Gea) and a fair number of decent ones. New back line plus two or three midfielders/wingers and they are good to go. A fair number need selling, of course. I know nothing about Van Gaal as a person but folks say he has a good track record.
Spurs made a mess in the transfer market last year. But they do have some decent players. If Benitez had that team give or take a few, it would fight for fourth.
I think it will be tough for everyone next year. Especially if Everton and Liverpool can keep their teams together.