Welcome to Flyertalk TravelFarWide.
I had a 64K in December for a flight to JFK. At check in, the OH and I paid o upgrade to F and really enjoyed the CCR (realise you get this anyway), the service, food and wine at the start of our holiday.
If you have the Avios and do not have any immediate or future pressing use of them, then I would certainly consider doing it.
64A and CW will be fine but for those of us who do not travel F all the time, it is still a treat and one that you can get relatively cheaper on this occasion.
Please let us know what you decide.