I've been writing programs using VIs and subVIs for over a month now and comfortable with those, but I want to teach myself how to use VISA sessions as well. Where is a good place to start or tutorial on this?
The first place I would look are just the example programs that ship with LabVIEW. Keep in mind that some of the good VISA examples will actually be defined as being for Serial or GPIB etc. If you are interested in some of the more advanced possibilities, check out the Instrument I/O VISA section of the Developer Zone Resource Library.