If you like Nicola Upson's series featuring Josephine Tey, you might enjoy Frances Brody's Kate Shackleton series set in Yorkshire in the 1920s. Kate lives in the area of Leeds where my dad used to live and we moved nearer there when I was 10 and a lot of the settings are places that we'd go to for days out etc.
Barbara Nadel has a series set in Istanbul with over 20 books, and at least 6 books so far in another series set in London.
I echo recommendations for Peter Robinson's Banks books, another series with more than 20 books,
John Harvey's Charlie Resnick books (Nottingham)
Stephen Booth's Cooper/Fry series (Derbyshire Peak District)
Again, people have suggested Ian Rankin's Rebus books
Denise Mina has a number of series and standalones, mostly set in and around Glasgow.
An older series I love is Patricia Hall's Thackeray and Ackroyd books, again set in West Yorkshire.
Stuart Pawson's Charlie Priest series
John Baker, series set in York