I've got tons of advice (of course), but since you're stuck in Illinois you'll probably end up flying on a US carrier. My first bit of advice:
DO NOT FLY ON AN AMERICAN CARRIER. Check out round-trip flights or connecting flights on
LAN Chile (great airline) or Panama's relatively new airline (forget the name, but you can find it easily enough) from LAX, Atlanta or Miami airports. Those living remotely near California should always check out departure and return flight schedules on foreign carries. Once you've found a good itinerary, then book round-trip flights on Delta, United, or American, (never Southwest) if you plan on being assured of making your connection to the non US carrier. The main reason for not flying an American carrier: lousy service. Even
Aerolineas Argentina, which proabably has the oldest fleet of equipment of any airline, treats EVERYONE like a human being, offers frequent and generous refills on free wine and spirits as well as has much better airline food.
LAN Chile (sometimes called LAN Peru) currently offers a "see South America" ticket that allows you to pick the destinations you want to go and rolls it all up into a round-trip ticket. If you buy a ticket with LAN be sure to sign up for their air miles/kilometers program at the same time. If you've got skymiles with an American carrier, use those miles to buy your tickets to and from the connecting cities where you'll board the non US carrier. Sometimes, even Kennedy in New York (Flushing) shows up as being a place for South and Central American airlines to take off and return. If you can decipher Spanish, check out
despergar.com. It's an online booking service like Priceline or CheapTickets.com. Otherwise, go directly to the airline's web site to check prices. It's a rare thing these days when a travel agency can help you find a better deal than you can on your own. But check with them, as well. In fact, if there is a travel agency near you that is owned and run by legal residents of the USA who are from South America, go talk to them first. Trust me when I say "This is Debbie, how may I help you?" who answers Delta's, Continental's, or American's 800 number hasn't the slightest clue how to help you get a good deal -- or even figure out if her company flies to the city south of the USA border.
Panama, the city and the country, are great places to vacation. It's hot and humid, but beautiful and the only thing you really need to worry about is making certain you have a polio booster shot and a yellow fever inoculation. There are mosquitos and malaria still exists in Central America, but Malaria also still exists in parts of Florida, Alabama, and Mississippi despite what the CDC wants you/us to believe. OFF is readily available in all drug stores and markets. So there's no need to pack your own.
Colombia is relatively safe as a travel destination these days, despite all the sabre rattling from its neighbors Ecuador and Venezuela. Bogotá is really an amazing city. Calí and other out-lying smaller mountain cities are a bit riskier.
Santiago, Chile, is almost impossible to avoid when flying non US carriers. But that's not a bad thing. However, there is no reciprocity agreement with the USA and Chile. Therefore, if you plan on visiting Santiago (which is really an eye opener, Manhattanites move slower and seem to do less world business) you'll need to pay U$S100 for a visa when you arrive at the airport. Canadians have to pay about 130 Looneys. But the stamp on your passport is good for 10 years or as many years as you have on your current passport. If you're just changing planes in Santiago to get to Brazil or Argentina, you don't have to worry about paying for a visa.
Buenos Aires became THE place to travel in 2001 when the Argentine economy collapsed. They defaulted on their IMF loans and could not make any guarantees that the money would ever be paid back. Suddenly, Buenos Aires and all of Argentina became a bargain for 'Mericuhn travelers. In some ways it still is. However, they figured out a way to satisfy their IMF debt. They import very little -- almost nothing. And they export everything that isn't nailed to the floor; all in an effort to whip the economy into shape. It's still a good bargain for 'Mericuhns, but inflation is quickly eating away at what was only a couple of years ago a great place to lavish yourself with taxi rides and seven-course parrilla dinners. Also, unlike other South and Central American countries, Argentines do not speak Spanish. They like to tell you they do, but they in fact speak a specific dialect known as Rioplatense which is a fusion of Castellano (Spanish) mixed with a lot of Italian, a side bar vocabulary known as lunfardo that defies interpretation because it constantly changes, and everything is inflected as if they were Italians arguing in the cafés of Rome. It's very difficult to understand. But it's a beautiful country. You can find accommodations in boutique hotels for $25 a night. But the currently the Puerto Madero section of the city (think the deteriorating warfs skirting Manhattan) are now where all the new hotels that run $300 on up a night. So, if you really need to stay at the Hilton, that's where you'll end up. There are much better deals.
As for my original caution about not flying on an American carrier, it is not because I hate the USA. It's because US airlines have been doing whatever they can to stay in business and still make a profit. Delta's planes are the filthiest airliners I've ever been on. Northwest is famous for, well, if you paid any attention to the news -- poor maintenance. United, which used to be "the friendly skies" has seen better days. And no one -- including any employee of any of the US carriers -- has been able to satisfactorily give me a reason why a can of beer should cost U$S5. I'm not a major imbiber, but wine, beer, and spirits are free on non-US carriers. Since degregulation of the US carriers it's been and dog-eat-dog business trying to keep a US air carrier afloat; which is really too bad. All the world's airlines have their problems, but if only Delta could get their shit together and offer service comparable to British Airways. Then again, if fishes had wishes . . . as my grandmother used to say.
A great place to visit (because it's so strange and beautiful) is Guatemala. The country is the most exotic and strange place I've ever been in Central America. Peru has it's good points of interest, too, and is reasonably safe. Ecuador is stunning, but the US government has never been too keen on making nice with whatever party or president is in power. But Quito, the capital, is as safe as Europe. Guayaquil, the largest city in Ecuador that 99% of 'Mericuhns have never heard of, is also a great place to have a bit of a wild time, but it's best you at least be able to communicate your needs in Spanish if you plan a visit to that quilambo. Bolivia is relatively safe, but the US State Department would prefer no one travel to that impoverished country. Still, it's stunningly beautiful and the indigenous people are the sweetest people I've ever had the pleasure to meet and live among. Probably the most dangerous place (except for Venezuela at the moment, which is too bad, Caracas is a Hell of a place) is Paraguay. A pseudo official (for no one really knows who's in control in Paraguay) said to me over dinner recently, "With enough money you can get away with anything in this country." And he wasn't smiling when he imparted that information.
Also, if you're planning on going south of the equator (ecuador, in Spanish) from the end of April to the first of November, remember to bring some warm clothes and a coat. Fall began in the Southen Hemisphere on March 21st. Winter is soon to follow.
Have a nice trip.