I can't believe anyone recommends NCIS, the 2nd-rate CSI clone for people who find 2 official spin-offs including the spoof that is Miami, are not enough. And you're saying they even did an NCIS spin-off? Americans will genuinely watch anything, it seems.
NCIS is actually a spin-off of JAG, a long-running Naval courtroom drama - though like any police procedural it shares certain common elements with shows like CSI. I personally always found the cast of NCIS far more likeable than any of the CSI casts (though CSI NY runs a close second, I guess). The characters all have a lot more personality than CSI allows, and the regular multi-episode story arcs allow a lot more character development than CSI's single-episode cases.
If you want a lighter-hearted police procedural, I think The Glade does a pretty good job of balancing humour and depth. All of the past season appear to be available on Hulu as well...