Punchy, from my research and experience here is an answer to your questions.

UofP is expensive and very large.  If your employer is paying for your education then they are a strong consideration, but if not, I'd keep looking.  Additionally UofP uses a lot of group or cohort style work.  Personally I'm not a big fan of that but some people like that.  I'm not sure if their undergrads are cohort or not.  Also UofP has a bad reputation with some because of aggressive advertising techniques.

Kaplan U.  I was a student of theirs for a while.  It was adequate as far as materials and content, however like UofP they are expensive.  They hide this fact by reducing tuition per hour and raising the hours per class.  Also they are very large.  By large I mean expect to be handled in a very non-personal, bureaucratic way, red tape, hoops, voice mail, etc.  I’m sure UofP suffers from this “large school syndrome” as well but I could be wrong. 

The Art Institute Online is nationally accredited I believe.  This may not be a big deal to you and that’s okay, but it is a huge deal to a lot of people.  If you plan on ever going to grad school or teaching a NA degree will have some severe limitations.  For the money and effort spent, I’d look elsewhere if other options are available to you.

Regis is a good school with a good reputation.  Expensive, but it may be worth it.  I would give it serious consideration.

Ashford University is a very small school that is trying to grow.  Expect a lot of individualized attention from them.  They also use an accelerated format, so you get your degree faster, but it’s going to be more intense than a traditional semester based school.  Another strong point, if you’ve never done a FAFSA or financial aid, they’ve got a ton of help for you.

So really, I’d think your most viable options would be between Regis and Ashford.