Sanford Brown in Altanta is an accredited program, so would be a good one to look into. You might call one of the program staff and find out what their graduate's rate of passing the ARDMS exams. This will give you a good idea of how well the students are learning from that program.
When thinking about entering an ultrasound program, you need not be concerned so much about certificate vs. degree. What is important is that you go to an ACCREDITED program, whether it is college or hospital based. An accredited program allows you to take your registry (licensing) exams upon graduation. Once you get licensed, you will never be asked about your schooling again. An employer does not care what route you take to get licensed, they just want you to have that license.
Don't waste your time or money on a NON-accredited program. Upon completion and graduation from a NON-accredited program, you must work in the field of sonography for a full year prior to taking your licensing examinations. But, you will have a hard time finding an employer to hire you, unless you are licensed.
I would suggest you observe an imaging department to get an idea of what ultrasonographers do daily. There is much more to it than scanning pregnant women. Most people have no idea how much is involved in this career!
There is a high demand for sonographers. The job outlook is this:
"Sonography is a dynamic profession that has grown significantly over the past 20 years. With rapidly developing new technologies and increased use of diagnostic ultrasound procedures, growth is projected to continue in the future with employment opportunities for qualified sonographers in both urban and rural areas nationwide."
http://www.ardms.org/default.asp?contentID=874 The American Society of Radiologic Technologists just did a large salargy survey. In Georgia, the annual average income of a sonographer is $65,980.
http://www.asrt.org/media/pdf/research/wss2007/wss07annualcompensation.pdf