We have a site collection that we are going to move to another web app.
This site collection has subsites that each have a data view web part
that I created. The data that the web parts are viewing also lives in
this site collection.

So, when we move this whole site collection, what's the best way to
point these web parts to the correct place, and not have to go through
and re-create each one? Is it as simple as changing the GUID in the
code?

I do know that these data view web parts are going to break, but in the
past I've just had to re-create them from scratch. I'm trying to
anticipate it this time.