Never really had pet peeves when I did ATC. A few observations:
1. Not cancelling IFR while good VMC to an uncontrolled airport with traffic to follow. Odds of crashing after switching over to CTAF 5 miles out and no one hearing / seeing it is remote. Just cancel...unless you're in BF Egypt.
2. Don't assume ATC is going to issue you traffic on something just because you see it.
"Approach, do you have traffic at my 3 o'clock, and slightly high?"
"Affirmative, I'm talking to him."
"Well...did you plan on telling me about him?"
"Negative. That traffic is 4 miles away from you, 500 ft above you, and going away from you. Traffic is no factor."
3. You can call "radar contact" or "got'em on the fish finder" all day but until the controller hears "traffic in sight," the controller is just going to keep issuing traffic. Most pilots realize this though.
4. Don't call back 3 seconds after your initial call if the controller doesn't answer. They're on the landline. One of the reasons why I always preferred a "wake up call" for FF.
5. You can switch over to FSS to get a weather update, but they're just going to read off the same CWA that approach has. Plus, approach has real time weather radar that's only 30 secs old.
6. "Approach, are we cleared to transition thru the class D?"
"Affirmative."
Never had any problems with large patterns, slow taxi, pilots talking too much or not checking in with ATIS. Then again, my airport ops were mostly fighters. They don't have those problems.
Oh yeah, don't be this guy.
Warning! Language.