We have all the major bestselling mystery series such as the Sue Grafton's "Kinsey Millhone" books ("A" is for Alibi, "B" is for Burglar, etc. [all F GRA]). We also have some series you may not be familiar with, but, which you might find enjoyable:
Beaton, M. C. "Hamish Macbeth" series, which includes Death of Yesterday [F BEA].
Dorsey, Tim. "Serge Storms" series, the latest being The Riptide Ultra-Glide [F DOR].
Fluke, Joanne. "Hannah Swenson" series, Red Velvet Cupcake Murder is her latest [F FLU].
George, Elizabeth. "Inspector Lynley" series [F GEO]. A new title, Just One Evil Act, is due out later this month.
Johnson, Craig. "Walt Longmire" series includes A Serpent's Tooth [F JOH].
Nesbo, Jo. "Harry Hole" series [F NES]. This Norwegian author, is now being promoted in the U.S., probably due to the success of Stieg Larsson's books. Police is due to be released next week.
Quinn, Spencer. "Chet and Bernie" series, the most recent is The Sound and the Furry [F QUI].
Willig, Lauren. "Pink Carnation" series. The Passion of the Purple Plumeria just arrived!
If you're a mystery series reader, you should probably visit Stop, You're Killing Me!, a site that lists "over 4200 authors, with chronological lists of their books (over 47,000 titles), both series (4900+) and non-series."