I just recently made the move from using a white MacBook 2009 and Snow Leopard, and an external monitor, as my daily workhorse. Many years of tried and tested, reliable service.
I love Snow Leopard. Despite having two fairly recent MacBook Air machines, an eleven-inch and a thirteen-inch, both upgraded to El Capitan, I was happy sticking with Snow Leopard on the much older laptop, as far as my daily work routines were concerned. I used to access old AppleWorks files occasionally, too, via Snow Leopard (which you can't do in later OSs, I believe), and I also happen to think that Snow Leopard was the last of the old-school 'real computer' User Interfaces from Apple. I am not keen at all over the way Apple's software design has gone, certainly in its visual embodiment. I have trouble figuring things out sometimes when I used to be led in the right direction previously and learned quickly, and while my eyesight has deteriorated as I get older, some of the OS on-screen fonts and colours these days leave a lot to be desired. Other things, too, like scroll bars, I find less functional than they used to be (but oh so clean looking in the modern design; give me functionality any day, however).
Eventually, the old MacBook began to find the challenges of daily use (I'm a freelance editor at a magazine) more difficult. Apple Mail was flaky (attachments not appearing reliably), some websites no longer afforded Snow Leopard access, and of course, there were all the other software and security updates it was no longer able to benefit from. So while I had used El Capitan and the MacBook Airs intermittently, I still miss my old Snow Leopard, a little slower though it may have been, and am still ironing out the anomalies that have resulted from a new set of routines and newer hardware/software.
I upgraded my wife's old MacBook Pro (about the same age as your machine) to El Capitan, and it seems to be behaving itself, but as she doesn't use it for much apart from e-mail, web browsing and some text work, I can't say too much about the outcome with any accuracy. Her machine has 4 Gb of memory.
Maybe it's time you bit the bullet and got a new Mac, and get to grips with it while you are still using your old machine for now? That way you'll have your old, familiar work routines until you can gradually move entirely to an up to date way of working. It has to happen eventually.
That's been my experience, at any rate. Good luck.
