Make sure that the online program is accredited by the appropriate regional association. Here is the list:
http://www.chea.org/Directories/regional.asp
An unaccredited program is a waste of money and time.
If you don’t want to go past a BA or BS, that is probably sufficient. But if you want to pursue further professional or graduate education, it will really help if you are able to get to know some faculty who can write you a letter of recommendation! Check out the programs and find out how much contact with real faculty you will have.
FWIW, you can also go to a famous prestigious university and not have much contact with real faculty. I did, and ended up not having any of my undergraduate faculty write letters for me to get into graduate school. And I know of others who have had the same experience.