There are nine seasons so far, and a tenth on the way. They also say it will be the last, but they have said that multiple times before, so who knows really.
Yeah - my wife really enjoyed Castle. Not sure why I never developed any affection for either lead. And the female cop took the concept of kicking down doors in high heels to a new level of ridiculousness! 
Bones was one of my fave shows for several seasons until the 2 leads hooked up. After that, I considered it near unwatchable. She got more and more extreme and they turned him into a clown.
Not sure how many of these made it to the US, but Paul Abbott, who wrote Shameless also had a series called Clocking Off, an ensemble piece set in a factory, and another called State of Play, a whodunnit set in the world of politics (on which topic, you could do worse than the original version of House of Cards).
Mention of Pie in the Sky reminds me of another series that keeps being re-shown on archive channels here: Lovejoy, starring Ian McShane as a “lovable rogue” antique dealer, who sorts out assorted intrigues and real crookery.
You might also like the work of Kay Mellor - more ensemble pieces: Fat Friends, on the members of a slimming club, and The Syndicate, each series featuring a different group of people forming a lottery syndicate.
And of course there’s Sally Wainwright, who wrote Gentleman Jack, Last Tango in Halifax and Happy Valley.
We just finished bingeing Person of Interest, and it fits the bill perfectly. It’s a drama about the rise of AI and government surveillance, but it’s also surprisingly funny - usually in a deadpan way.
For example, a scene where one of the leads is cleaning a sniper rifle on the table, and the other says “I’d prefer it if you didn’t do that here.” The response: “When I do it in the park people look at me funny.” The show is just full of little quips and one-liners like that.
It’s also a great show on its own merits. I’m very sensitive to ‘technobabble’, but this show at least gets the babble right. Their tech advisors are very good.
The show got a 100% rating on Rotten Tomatoes for four of its five seasons, it has the one of the highest ratios of episodes rated over 90% of any show, and one of its episodes ( “If-Then-Else” ) regularly makes it onto ‘best TV episodes of all time’ lists.
It’s on Netflix.
Seconded