I actually discovered Doctor Who through Sherlock, since they share some of the writers (well, Moffat), and then some people at a Doctor Who fan meetup recommended that I get into Torchwood, which I love too. It's quite short; just two seasons then two miniseries constituting seasons three and four - those last two are pretty heavy but the show's amazing too.

Never saw Castle or The Mentalist, though I've heard the latter incorporates some Sherlock Holmes-esque tropes. I do recommend Life on Mars if you think you might be interested in the story of a 2007 cop going back to 1973 and trying to cope with the different approach to his profession back then. :) (Such a good show...) And nice to hear from you!