There is always Colorado Free University
http://www.freeu.com/spanish/. I have not taken classes there myself , so cannot vouch for them. I do attend some of the "meetup" groups whenever I have time. Very useful.
http://spanish.meetup.com/cities/us/co/denver/
In my experience, there are two syles of learning a foreign
language: some people can just absorb it (Rosetta stone style), other have to sit down and study it (traditional classroom style).
I'm the second type. Rosetta Stone was a waste of time and money for me. I have to study how things work (verb congugation, etc) first before I start trying to speak it.