Go see the wonders of the world. Be in awe.
I would suggest India because it's a microcosm. Go north to the Himalayas and you can feel the majesty. Head to the west to the slums of Mumbai and you will understand poverty. Maybe go learn to meditate out there at a vipassana center. Visit Agra and the goggle at the opulence of the Taj Mahal. Then head to Varanasi and experience the rawness. Maybe you'll even see a miracle or two if you're lucky. Go to Hampi and see giant boulders stacked on top of each other like lego and be bewildered. Stay in a palace just for the hell of it. Take a motorcycle through small villages and be greeted by the children who've never seen anyone so pale or so dark. Sleep in a tent in the deserts of Rajasthan. Visit the holy places and wonder at the peacefulness.
But then again, India isn't for everyone, but it does have everything.
I'm Indian, so I'll add a few, particularly about some areas that are likely to be less well known to foreigners who may mainly have read or been told about the most popular tourist areas, such as the Golden Triangle (Delhi/Agra/Rajasthan), Goa and Kerala:
Go to parts of central India, e.g. Madhya Pradesh (MP).
https://en.wikipedia.org/wiki/Madhya_Pradesh
It's a big state. Lived there for some years. Apart from the usual touristic areas, of which there are some, try to check out the central Indian deciduous forests, comprising sal, teak, and many other species. (India has huge biodiversity.) I really enjoyed the many hikes I did in those forests.
Kanha National Park.
https://en.wikipedia.org/wiki/Kanha_National_Park
It has those deciduous forests I mentioned, with fauna that include tigers, gaur (Indian bison - the world's largest bovid), dhole (Indian wild dog), barasingha (swamp deer with 12-tined horns), etc.
https://en.wikipedia.org/wiki/Bengal_tiger
https://en.wikipedia.org/wiki/Gaur
https://en.wikipedia.org/wiki/Dhole
https://en.wikipedia.org/wiki/Barasingha
Marble Rocks - sheer marble cliffs on both sides of the Narmada river near Jabalpur (MP). They offer boat rides down that stretch, so you can see the cliffs from up close. Seen it.
https://en.wikipedia.org/wiki/Marble_Rocks
In South India, less well known places include the "hill stations" (resorts) such as Kodaikanal, Coonoor (5-7000+ feet high, with a cooler climate, and mountain forests and orchards), many less frequented and less crowded beaches, etc. Temples are well known but there are a huge number of them, large and small, many with interesting architecture. Many wildlife sanctuaries in South India too. Seen wild elephants on hikes from the mountains to the plains. Bison too, many times, from nearby. They're huge, but peaceful, unless disturbed. Cape Comorin (Kanya Kumari), the southernmost tip of the Indian peninsula, where the Arabian Sea, Indian Ocean and Bay of Bengal meet. Multi-colored sands there.
Seen some of the above.
The Western Ghats, a long mountain range down the western side of India, right from Mumbai to almost Kankyakumari, including the states of Maharashtra, Goa, Karnataka and Kerala/TamilNadu. Lived in parts of it for some years. It's a biodiversity hotspot, with both deciduous and rain forests.
https://en.wikipedia.org/wiki/Western_Ghats
A concert about India's environment and the Western Ghats, by Chinmaya Dunster and the Celtic Ragas band - A Sense of Wonder:
How about climbing Mount Kilimanjaro (takes a week), then relax on the beach for a week and give the remaining 15k to a local orphanage?
Pick different culture. Stay in one country/city, exploring it to the fullest, making friends. Learning to sign their songs.
Going for refreshment and nature ?
Hop in multiple places.
- Spokane WA, - Glacier National Park MT, - Waterton National Park AB, - Banff National Park AB, - Jasper National Park AB, - Kamloops BC, - Vancouver BC
I will highly recommend trip to national parks in North America.
Last year, for about $15K, my wife and I travelled to Japan and India for 3 months. While 15-20K is plenty of money, 2-4 weeks is not enough to travel to lot of different places (multiple countries), may be enough for a decent size country. If you are into nature and hiking, I will suggest Peru.
Just for comparisons, about $25K is pretty good chunk of amount for a solo travel to go living around the world for entire year.
Not sure if you're being humorous but, from the west coast of the US, it's still a shorter distance to get to Kenya if you go east than it is if you go west.
I bet I could spend upwards of $2k in four weeks if I really tried, but honestly the places you'd have to stay and the things you'd have to spend your time doing would just be way too unpleasant. Think Cruise Ships, Hotels where people are wearing their Yachting Clothes, God forbid, Guided Tours.
It's just not worth it. Either save most of your money or find a way to get the rest of that year off, then go out and have some real fun
If you really want to burn the cash, then spend another 1k on a day trading class along the way, and put the last 19k in a highly leveraged investment like options on GLD or something. Either way the investment goes, it'll make your trip a lot more exciting!
I'd spend all 4 weeks in an area where I don't fit in. Some South American country probably, perhaps Peru. As an Asian American, I think I'd feel too comfortable in any American, European, or Asian country. In South America I'd be able to challenge my comfort zone.
I'd use the money to take necessary precautions on necessary resources and safety, but otherwise, I'd go lean and rather push myself to do things and meet people there. I think 4 weeks is a good enough to time learn a new way of life and really change how you see things.
Then write book or blogpost about it :-)
I'd take 2 to 3 days each city, then book a plain/train and move to the next... Take camera (new mobiles are good) and a diary (digital if you like). Eat specialties and drink the wines and juices each place makes. Talk to people a lot, write your experiences and think. Seize the moment when you find something awesome... Take pictures and videos afterwards :-)
Also check out my feed of some blog posts with images of nature, from different countries, including some of the above:
This guy has done it twice and raved about East Africa https://en.wikipedia.org/wiki/Jim_Rogers
From my perspective I would hit the countries with the most people - China and India and then spend a week or so relaxing somewhere (Southern Europe(Greece Spain) or Israel)
If you want to know the big cities, including culture, I'd go to Europe. In four weeks you can visit culture capitols as Paris, London, Madrid, Rome, Berlin...
Looks amazing.
With 2 weeks I'd possibly go to Antarctica because that's the only continent I haven't yet visited. With 4 weeks I'd visit the Galapagos, and walk some of the Inca Trail to Machu Picchu. Or I might go to Greece.
Btw a decade ago I traveled around the world for one year, for less than that amount. Best year of my life.
Having said that I found travelling alone to be quite lonely, even if I spoke to and socialized with people along the way. The best way (for me) would be to go with a friend or even better my family.
As for where to go. I would love to see more of Tasmania or NZ. Far northern or eastern Europe too. Get away from the cities and see the amazing scenery.
Ideally you would do two trips: one during the snow season and the other when it's warmer for the hiking season.