That's a pretty broad request. How about narrowing it down a bit. Are you interested in max miles or just sightseeing? Any required stops? If sightseeing what do you like to look at: beaches, mountains, jungles, deserts, history, architecture, ...??? How long do you want to spend in any one place during the three weeks?

What class are you planning to fly in? Do you want to originate in CPH or somewhere less expensive, e.g. CAI?