Some people don't care about instruments, as long as it's good music, it doesn't matter...but personally...there are instruments that just resonate with me in different ways. Like, certain pieces wouldn't sound nearly as good without them. If you feel the same way, introduce a certain instrument/family that has you transfixed and infatuated. I'm going to start with a little bit about the mandolin family.
I've known of the Mandolin for awhile, but it wasn't til about 2010 that I really began to be transfixed with it. It first started in a bluegrass setting, as you might expect, it was always the same time I really started diving into bluegrass, but that's another story entirely. There was just something about the way people played it, the way it sounded, the tone, the look...it all just started digging at me. So in 2011, I traded all my musical gear for a banging Mandolin...but eventually had to sell it. It really was a joy to play, I'd recommend it to anyone that plays an instrument.
As far as the tuning and register goes, it's tuned exactly the same as a violin, GDAE in that upper register...which kinda deters me a bit, I'm not a fan of the super high registers, I prefer something that sits around the same place as a guitar, but the mandolin isn't the only instrument in it's family. There are alterations in the same vein as the violin: Mandolin, Mandola, Octave Mandolin (same tuning, just an octave lower than a standard mandolin), Mandocello and Mandobass (which is rather uncommon for obvious reasons).
I'm a laaarge fan of the Mandocello, which is tuned, as you'd expect, like a Cello. It sits in that nice pocket that I love. The thing about the tuning that I DON'T enjoy is tuning in fifths. It's easier with a mandolin, with such small distances, but a mandocello makes it seems like a pain. On the plus side, every chord is movable. But these are all temporary problems, I'm sure. Once you get used to the new tuning, it will be just like any other instrument.
It's hard to explain, but the mandolin family just has a really nice baroque sound that I absolutely LOOOOOOOOOOOOOOOOOOOOOOOOOOOOVE. It fits with Celtic, Bluegrass and classical compositions, all forms of music I adore. Vivaldi - Concerto for Mandolin in C Major RV425 - YouTube probably one of my favorite pieces written for mando. I could go on...but I'll stop here for now, I have other instruments I'm sure I'll gush about in the future.