I actually have had Good Omens on audio for ages, but haven’t gotten around to it. I just bought Small Gods – I think I’ll start with that one, and then jump around at random. I have a feeling that it doesn’t really matter about following one book to the next with Terry Pratchett – but I could be wrong. 
Do the stories flow in cycles and blocks of books, or is it okay to read them in any order?
The BBC recently (last December) broadcast their radio adaptation of that one. They’ve also made adaptations of Nation and a few of the Discworld books. They’re all good, particularly Nation, so if you like radio theatre, you may want to keep an eye on the BBC site - they’ll probably be broadcast again, and when they are, they’re freely available online for 30 days.
So, so much 
Yes, very well spotted!
I think the Patrician we see is always Vetinari, even in the Colour of Magic. Because of the dog. What you get is a whole lot of Archchancellors before Ridcully.
The BBC will be re-broadcasting their adaptation of Good Omens, the book Pratchett wrote together with Neil Gaiman (and it was Gaiman’s first novel). After broadcast it’s freely available online for a while (it’s usually 30 days).
Good Omen’s is not my favourite story from either of the authors, but as we’ve seen in this thread others rate it higher. I heard this adaptation when they first did it, and it’s well done.
Awesome, many thanks!
Neil Gaiman’s first (half of a) novel? I didn’t know that!
You might be interested in this video, where Neil Gaiman among other things talks about his friendship with Terry Pratchett and the history of Good Omens. I found it well worth watching.
Edit: And now that I found myself re-watching it, I’ll also add that it’s quite moving.