I was pretty excited when I worked out what it meant for the J boarding pass to be rejected out of the machine when boarding an A380 on SYD-SIN-LHR flight 12 or 13 years ago!  Yes we were upgraded to F (for the SYD-SIN leg).  I contained myself because I did not want to look like an amateur, but soon gave that away by asking the flight attendant to take a photo of Mr Seat0A and me.  "Oh, is it your first time?" she said, with a twinkle in her eye and then proceeded to give us the absolute best service, some helpful tips and seat orientation and so on.  When I thanked her, she said that she loved loved loved it when people acted excited to get an upgrade and were not too cool for school.  I was WP at that time.
I was not excited in 2015 when QF1 SYD-DXB-LHR was delayed over night for mechanical reasons (but that's a whole other story).  We just accepted it, took the night in the nice hotel and returned to the F lounge for early breakfast the next day - to find that we had been upgraded to F (from J) the whole way.  I often wondered if it was a good will thing for high status pax (I was P1 at the time) or if it was because we acted like civilised humans about the delay - boy there were some rude, over-entitled people harassing the F Lounge staff.  I was pretty excited about that one.
On QF2 LHR-DXB-SYD in about 2017, we had lovely service in the EK F Lounge and I asked to see the manager and gave a compliment for the staff member.  He asked if I would be prepared to write it down and sign and I said of course.  He thanked me.  Some while later he tracked us down in the lounge and said he had a new boarding pass for me and Mr Seat 0A.  We were now in F from DXB-SYD.  I was quite excited about that too but tried to retain some decorum 

. I was P1 at that time.
These are the only times I have ever flown in F.  It was lovely, but I don't think I could justify paying for it, so J is my happy place.  Of course, I hoped to be able to use my points and status to get F award seats or F upgrades, but firstly I dropped from P1 to WP when I stopped flying for work so much, and then of course all the issues with using points to get CR seats mean that I will probably only ever fly F when I get a free upgrade.  So I reckon I will remain pretty happy about that!