What to do at 80?
If it is about open zones you can fool around in: in the west there are drytop and silverwastes, and from lions arch you can use the consortium portal to get to southsun cove.
Boxfarming though is most likely going to happen in frostgorge and Orr, since SW and DT have their own system about loot and stuff.
Oh and if you are looking for really specialized high level content to do at 80 and you have some people to play with, you might want to give the fractals of the mists in lions arch a bash.
A few more good suggestions here:
https://forum-en.gw2archive.eu/forum/game/players/what-to-do-after-lvl-80/first#post4900138
Having levelled 14 character, visited all of the story for human, sylvari and much of asura characters, world completed 5 times etc, I am at a loss for new things to learn and discover myself.
My game time mainly consists of trawling LFG looking for people who need help.