Sounds like I am playing the game just like you and your mates did. Taking it slow. It's fun to get those levels on all the skills up pretty high. Some of them aren't just decrease in required stamina...for example, a high jump and high run level makes for some fun gameplay lol

I would say, take a break until the additional bosses are released, or do a PvP with your clan with different teams. Each team gets a certain amount of time to build their base, then you have to go on raids

You could also do a giant capture the flag game with a sword as the flag or something

Even though you've reached endgame for now, doesn't mean the little minigames need to end. :)