We have a total of 11 days. We will arrive late Sunday night in Lima. Is it worth spending a day there?
Our base for the first week is Arequipa where the conference will take place so we have to stay there for a few days. Can we do a day trip to Lake Ttikaka? What else in Arequipa?
Then, we can go to Kuzco for about 6 days. What is the best way to travel around there? How long do we need to get used to the altitude? My husband and I are in our 50s and our son is 19.

Yes Lima is worth a day or more.

Arequipa is great colonial city

Tour Colca canyon from there

Titicaca to far in a day do an overnite at least

on your way to Cusco.

www.cruzdelsur.com.pe best bus.

Would take Diamox for altitude illness prevention

especially visiting Titicaca islands 13000 ft.

I might recommend visiting Lima at the end of your trip if you have that option. It can be a bit of a culture shock until you are 'into Peru'. But I thought it was worthwhile.

If there is an early plane out of Lima to Arequipa it might be worthwhile to do that, you can stay at the airport Ramada to catch up on sleep.

If possible do an overnight trip to Colca Canyon -- I think it would be a very long day to try and do it and come back to Arequipa in 1 day.

We spent a day in Lima at the beginning and another at the end of our trip to Peru. Didn't really care for Lima.

Everyone reacts differently to the altitiude. Arequipa is not that high, but Colca Canyon gets up there. Drink lots of water and avoid alcohol.

I would also spend some time in the Sacred Valley -- Ollantaytambo is fabulous and the ruins at Pisac were great.

Enjoy Peru

Yes, the Colca Canyon is well worth seeing and there are some fantastic hot pools nearby as well. There is a simple camp in the canyon itself (called the Oasis) which is an amazing place to stay and an unforgettable hike to get there. I was lucky - I did the hike with Miss Peru's sister! Have a look at http://www.jeremytaylor.eu/Peru_2002_1.htm to see some of the pictures.
Watch out for taxis in Arequipa (and everywhere in Peru). Best to get your hotel to call for one. My taxi driver took a 'scenic' route down a dark alley where four of his mates were waiting... Not a pleasant experience.

Thanks to ALL of you for the usefl tips! Yes, one day in Lima, Yes, one overnight stay at Titicaka, careful with taxi drivers. Maybe the Colca Canyon -if the conference has something organized already. Definitely Matchu Pitchu with good hiking shoes! Only 11 days! We will do what we can...
Very useful site and all the suggestions from other people's experience is great!