The Harry Potter series (seven books) as well as all the Sherlock Holmes stories (three volumes). By the time I get through both, it's been years, and I can start again at the beginning. :)
> as well as all the Sherlock Holmes stories (three volumes)
You may be interested to know Stephen Fry has done a 71 hour recording of all the Sherlock Holmes. He has an excellent voice for audiobooks.
The whole thing is a single item so if you're on Audible (for example) it's just one credit. And in a similar way to the ITV Jeremy Brett TV versions of Holmes, you get the whole canon of work with the same artistic vision.
The versions on audible have great readers IMO.