Yup,I've visited parks in Kenya,Tanzania and South Africa. In fact were going again in July. I've never personally seen an elephant acting aggressively but,as I said,there are many youtube videos. I guess you can say that when you're not threatening their young and you don't obstruct a young fella's path to females you'll be OK.
OTOH I could tell you a story of a rhino we saw in Tanzania. Even our guides were scared!