What do I do at 80?
Get caught up on the Living story event in Southsun Cove- you can get some back pieces you might want as well as decent drops from events there currently – this website will help http://dulfy.net/category/gw2/
As a level 80, you can get a guaranteed rare drop from each and all of the world bosses once per day (you are able to get more than that but you’ll get at least one). These websites can help you track the spawn times of World bosses on your server: http://us.gw2stuff.com/ and also http://guildwarstemple.com/ All you have to do is type in your server 
Fractals are always good to run as well as any dungeon you like and/or CoF path 1.
If you liked WvWvW last time you played you will see some changes there and some more on the way.
One thing I have done with my level 80s is get mats for my lower level alts to max out their crafting skills… it’s nice to add 20 levels to an alt in a short period of time 
Lots more to do but hopefully this will get you started. I’m afraid you missed out on Super adventure box and the Molten weapons Facility dungeon 