If you want a good police/crime book I would recommend John Sandford's Prey series. The first is Rules of Prey. They don't have to be read in order, although I think a couple might be sequels, but I can't remember exactly which ones, and they do sometimes mention something that occured in previous books.
For the classic closed room mystery Agatha Christie. She's a mystery genius and any book of hers is great. A few of my favorites are: The ABC Murders, The Murder of Roger Ackroyd, Murder on the Orient Express, and Crooked House. And Then There Were None is another of hers that is immensly popular.
A great military/lawyer series is by Brian Haig, the main character is very sarcastic, as is the author's writing style. His books are some of the few books that I actually laugh out loud during reading.
For Spy books I would recommend Daniel Silva's Gabriel Allon series. The first is The Kill Artist, or something like that.
And pretty much everything by Michael Crichton is good. State of Fear and Next are his weakest imo.
There are a few other series and author's I absolutely love such as Jeffrey Deaver's Lincoln Rhyme series, Douglas Preston and Lincoln Child's Pendergast books. Or Lincoln Child's solo novel Utopia is awesome, its about a super technological amusement park being taken over by terrorists.
Those are about all I can think of off the top of my head, but I have a feeling that's way more than you were looking for.