This is not uncommon in IT. I've always compared it to flying a plane. When you're doing your job, nobody notices it. The plane just magically opens up when you are at your destination.
I suspect that your problem stems from the fact that you are simply not promoting yourself and are going to far to be helpful.
What? Going to far to be helpful? How is that possible? Isn't that my job?
You said it in your question: You've been doing a good job for so long that your standards have now become the norm at your workplace, and nobody gets praise for being normal.
In Star Trek, Kirk asks Scotty if he always pads his estimates, to which Scotty says that it's how he maintains his reputation as a miracle worker.
There's is a simple truth to that, you need to MANAGE EXPECTATIONS
Don't be TOO available. When people tap you for your expertise, don't make it look easy. Do a bit of self-promotion, talk like an auto mechanic who just described how difficult it was to track down the intermittent problem that turned out to be three things going on at once.
For the ones that don't even thank you, make them sweat a little. If they take you for granted, let them wait a little the next time they need you.
Well, I don't know if I can get to this today...
might be enough to get their attention.
Back to promoting yourself. I had someone reporting to me who was great. You sound just like him. The problem was he was servile to the point of obsequiousness. He didn't like to promote himself, and he didn't like to make waves. He nearly ended up losing his job.
Draw attention to yourself. When you go above and beyond, make sure that people know it. A coworker of mine corrupted one of her files and asked if I could fix it. I said the following WORD FOR WORD:
If anyone on this earth can, I can.
I said that in a joking, over the top tone, but it was true nonetheless, and she was sunk without my help. You need to be the one to make them understand it.
- Make yourself less available. Scarcity makes value
- Manage expectations, just because it's easy for you, doesn't mean it's easy, let your coworkers know your value
- Promote yourself, brag about your skills THIS BOOK shows just how to do that.
- Command respect. Have people who don't express thanks by having them make appointments with you. This demonstrates that your time is valuable.
- Cut back on the overtime. If you act like your time means nothing, you will be treated as such.
IN SHORT, if you act like a doormat, people will walk all over you.