I'm aware now over the last 5 or 10 years that when you do an accent, you really have to kind of get down to the nitty gritty and go into the phonetics of it, if necessary. Find out not just the sounds but the rhythms and the music - or lack thereof - in a particular accent.
I do very few standards. Hardly any. Other people's tunes that I do are usually obscure tunes, for the most part, although I do a couple of Duke Ellington tunes that are well known.
Gil Thorpe is a great diversion and is to book writing as poetry is to prose.