Thanks to Bootsnall for making this possible,
I'm planning a trip from southern Peru into northern Chile and back through Bolivia (East of Lake Titicaca) via motorcycle. Followed by either a flight to Buenos Aires/ Montevideo or a boat trip from Iquitos along the Amazon.
It's a lot of stuff to pack into 2 weeks, but that's my style.
Questions:
1. If anyone has experience with rentals and can shed some light please do. I'm not interested in confining myself on a tour. Likewise, any info on motorcycle travel thru S. America is appreciated.
2. How reasonable/reliable are flights within S. America (i.e. from Cusco to Buenos Aires, not big airlines)?
3. For the bike trip, are there reasonable tea houses/ hostels along main routes or should I bring camping equipment?
4. Anyone been sandboarding in Peru/Chile?
5. Monetarily, is it easier to bargain with cash or should I rely on the exchange rate through the ATMs?
6. If you'll be in the area along this time frame I'm always looking to meet new people!
Thanks,
Mike

keep in mind this will be the rainy season. the rain behaves differently depending on where you are. in arequipa and cusco, it can rain for hours.. it's not like in the amazon or other tropical areas where it gets super torrential for 10 minutes and then you're good for the rest of the day. pack a LOT of DEET and some of those candle things you can burn that keeps mozzies away. for the amazon. the mozzies ate us alive around xmas, despite the DEET.

sandboarding is very popular in peru.. we ran out of time so couldn't get to southwestern peru. but the lonely planet peru has a lot of info on that.

look into LANperu and aerocondor for flights. also, there appears to be two separate prices-- one for peruvian citizens, and a more expensive one for foreigners.. doh! you should probably book ahead though. they only have one or two flights to most cities each day.

what do you mean bargain with cash? you mean get a better exchange rate through cash vs withdrawing from an atm? it depends on your bank. my bank (bank of america) doesn't charge too much whenever i make an international atm withdrawal but my friend's bank (citi) charged her $60USD for withdrawing $200USD (not in peru though, just making the point that it's different for most banks). or do you mean bargaining with cash instead of using credit cards when you're out in town shopping and stuff? only some stores can take credit cards, and definitely don't count on street vendors accepting credit cards.

have fun!

I started reading the first line of your topic and thought - that would be a trip for months.
I'm not sure it'll ever be worth doing it for only two weeks. All the arrangements, stuff you need for a motorcycle trip, isn't worth it.
As the other poster said, you have to consider weather, especially rain. There are only main roads that are paved, in being on your own, you might be not safe, if you go off the main routes. Or, at least you can get stuck in mud several times and get a week delay.
You've got to reconsider you idea of travelling, and make it more realistic.