I'm an Ashworth College grad, and I found the correspondence method to be relatively convenient. They send you a workbook and you answer the assignments in it. You can submit your answers online and get pretty quick feedback. It's like the best of both worlds.
As an aside however, Penn Foster courses are ACE reviewed, whereas Ashworth is not. This will help in transferring credit, though I recommend that if you start a program, you finish it or you risk losing your butt in credit transfers anyways.
Both schools are weapons of "mass education" meaning that they enroll you quickly and run you through the system with little or no support due in part probably because of the sheer number of students they have at any one time. I was very frustrated with Ashworth College student support. Whenever I called it would be a miracle to get anyone on the phone if ever. Emails were seldom answered in less than a week and even then the answers seldom were thorough.
Either school has a quasi customer service where you do not actually speak to an instructor etc. But then they are both very inexpensive.
For the money, I'd take California Coast University over either, being that you get personal support, inexpensive tuition and you can pursue your degree up through the Masters level. http://www.calcoast.edu/
That being said, I do not regret my Ashworth College experience as it paid off. However both of my brothers enrolled and dropped out due to lack of support. For what it's worth.