I love crime shows and, yes, admittedly they might not be technically correct as far as the science and procedures go but it IS television. It's supposed to be entertaining and if they got too caught up in the science it would be a bit TOO technical and, dare I say it, boring. Plus, they have to fit an entire case into one show.... not easy if the characters have to wait weeks or even months for DNA results etc.
The same goes for the beautiful casts, it might not be very realistic but as already mentioned by others, it's the way it is as far as television and movies go. You just have to go with it.
My favorite shows are NCIS (I have a crush on Tony), NCIS: Los Angeles, Blue Bloods (which I've only recently gotten into), CSI: New York and my absolute favourite Bones... which if you don't watch you really, really should.
I also used to love Third Watch which was a little different because it was a mixture of Police and Fire Department and wasn't technical at all. I used to love the original CSI too but I didn't like it when they killed off Warrick and then with the loss of Grissom too it just didn't do anything for me anymore. I also watched The Mentalist for a while but gave up mid-way through Season 3 (I think) because it was getting a bit old. Every episode seemed similar to the last one.