The shower is rather a special experience, especially on your first A380 F flight, so that goes without saying.
Some F passengers like to frequent the bar (officially called 'lounge'), others don't see the need. Depending on my mood, I have done it once of twice but I usually don't bother (I actually don't fly F that often, mostly J with the occasional miles upgrade, an even more occasional paid F and a very rare op-up). At the moment, I think the on board lounge is still capacity controlled so the atmosphere will hardly be 'convivial'. Don't go to the lounge in your F pyjamas and with wet air, Aussies would say you look like a d**khead (which I personally think is true). Let the FA know you go to the lounge as she will offer to take the Dom (or any other 'premium drink') there for you to enjoy (no Dom in the lounge, just the J champagne).
My favourite part of the F experience is that you can have what you want when you want it. And the crew will fuss over you.

There used to be a 'how to maximise the F experience' thread somewhere, you may want to look for it.
Enjoy!