What do you recommend using for graphically visualizing a WSDL?

I have used SOAP UI with success in the past:

http://www.soapui.org/information/WSDL_Test.html?gclid=CMOpgKnAjpgCFRBbagodxyzOqg

It allows you test methods and to see if your WSDL passes current standards.

XMLSpy....nothing beats it (^-^)

I've had success with a combination of the Elipse WTP WSDL Editor and SoapUI.

Eclipse WTP WSDL Editor -http://wiki.eclipse.org/index.php/Introduction_to_the_WSDL_Editor

SoapUI - http://www.soapui.org/

Try this (online) WSDL viewer:

http://tomi.vanek.sk/