I love love love both James Patterson and John Sandford. James Patterson has two different series, The Alex Cross series and the Women's Murder Club series. The first in the Alex Cross series is "Along Came a Spider"...the first in the women's Murder Club series is "1st to Die".
And John Sandford has the Lucas Davenport series (he's my favorite fictional hero!!) and they all take place in Minnesota. The first book in this series is "Rules of Prey".... I just finished "Phantom Prey" the 18th in the series and I think there are still two more that I haven't gotten to yet.
Happy reading!