Texas doesn't have open-carry?
AZ does, but I don't think it's usually a good idea to let everyone know that I am armed.
Nope, until Bush signed the CHL law here in the mid 90's, it was impossible to carry at all in Texas.
I personally believe that the tactical advantages of concealed carry (low profile, and hidden from view) outweigh those of open carry (faster draw and a possible deterrence).
However, there are also 'political and social' ramifications that should be considered.
If more people open carried, then the police and general public would be far more acclimated to the concept of an armed public. This makes it more difficult to pass gun control, and it increases the number of people that are exposed to the gun culture, in a positive fashion.