Penn Foster High School has recently celebrated 125 years as a school. Clearly, that was not all online! I do know, though, that a long history like that speaks to the quality of its on-going programs. Also and importantly, you know that they are not going out of business any time soon.
One thing that I particularly like about Penn Foster is that it offers areas of concentrations in health care and in building technology. It also offers a high school with early college emphasis. In other words, you can earn college credit while attending high school. For specifics, read about the concentrations here.