T. M. Johnstone

A landmark work in linguistic fieldwork in the Gulf dialects of Arabic, from Kuwait to Buraimi. He seems to cover the variation in morphosyntax better than Hamdi Qafisheh, who mainly worked in the Trucial States (later the United Arab Emirates) and has less discussion of variation in his book.
Johnstone focuses on the basic structural features of each dialect, dividing his book into Phonology, Morphology, Syntax, and Texts. Each section has further divisions by location: Kuwait, Bahrain, Qatar (he has texts from Doha and Dukhan), Trucial States (Abu Dhabi and Dubai), and Buraimi.
Comparative dialectology is outside the scope of this book; he generally talks about one dialect at a time, leaving you trying to remember, for instance, which dialects included a feminine plural and which didn't. Because of the organization of the volume, it is difficult to find quick answers like that.
The texts are not particularly long but most of them are very interesting and enlightening on both culture and language.
In my opinion, Johnstone's work has aged well. He makes many statements, especially about the Kuwaiti dialect (which he breaks into Old Kuwaiti and New Kuwaiti), to the effect that "such and such form is probably obsolescent"; yet I have heard some of those forms still attested. Of course, all this depends on the age and upbringing of the speaker.
Johnstone's data from Qatar is unfortunately taken secondhand, and his only text from Dubai is full of MSA influence. There is no text from Buraimi.… (mere)