So my brother works for United Airlines and Im able to use his flight benefits every so often to fly standby out of OHare. Im planning on taking the week of Thanksgiving off to do a solo trip somewhere fun.

Here are some places I have already been:

Tokyo
Hong Kong
Madrid
Florence & Rome, Italy
Hawaii
Puerto Rico

Places Im considering are:

Tokyo/Japan again (I had a great time the first time, and maybe this time I could take a train to another city/town)
Seoul – Never been to South Korea and Ive heard its great
Buenos Aires – I know very little about Argentina but it looks cool and its summer there.
Lima, Peru – Not sure if Id have time to go to Manchu Pichu – what other things are there to do there?
Beijing – Hong Kong wasnt my favorite place, so Im not sure how I feel about going to mainland China
Lisbon, Portugal – My brother went and said it was great
Sydney, Australia – Sounds like a cool place, though Im concerned about the insanely long flight time from Chicago.
Frankfurt, Germany – I could land there and travel around a bit. This will probably worry the hell out of my parents because theyre concerned about me traveling in Europe after the recent Paris attacks. Im not too concerned about it, though Id rather not stress my parents out if I dont have to.

Im a 31 year old man and I like sight seeing, meeting cool people, checking out cool bars/restaurants, and outdoorsy stuff like hiking, cycling, etc.

Any thoughts? Is it a bad time of the year to visit any of these places? Particularly good time? Im alright with weather in the high 40s (f) and up, though I wouldnt mind going somewhere with great weather.

Thanks!