Is there a way to, I guess by calling setUp() and tearDown() only
once, which I don't think is available "out of the box", to run
multiple test cases on one browser instance?
Test A run on browser A
Test B run on browser A where Test A left off
i.e. bypassing setUp() except for the first test case and bypassing tearDown() except for the last case.
And I guess another nuance is I'd have to be able to identify which browser out of all the other browsers currently open...
TestNG/Selenium does that if you setup a Data Provider.
Software Testing, Second Edition: "Intelligently weighing the risks and reducing the infinite possibilities to a manageable effective set is where the magic is."