The Inca trail was the highlight - the main event we went for; after 4 days hard slog, it was amazing to come out at the Sun Gate overlooking the ruins at Machu Picchu
Also really enjoyed the Amazon - hot & humid, but worth all the sweat! don't go expecting big things - you'll hear more than you see. The noise the howler monkeys make is weird (if not a little spooky)
The homestay on Amantani Island was rather humbling; the family made us very welcome, and cooked amazing meals from nothing; they have very little but welcomed us 'gringos' into their homes
There is a lot of travelling and a lot of early starts on this tour - be prepared for it! and a lot of packing / repacking your gear so don't take lots of things you're unlikely to need
The hotels were a bit hit and miss, depending on which room you got - the second time at both Cusco & Lima were much nicer rooms than the first time; just generally could have done with a bit of modernisation.
There's chance to get laundry done in Cusco (before & after the trail) which is useful; take advantage of this & you'll have to pack less!
Sacred Valley trip from Cusco is worth it - good to prepare for the trail ahead; nice lunch & a bit of spare time to do the only real market shopping available
Although it was intersting to go to Lake Titicaca & we enjoyed the Island homestay with a local family, on reflection, it does seem like a lot of effort (i.e. virtually 2 full days travelling there & back). As we had very little spare time with the itinerary, it might have been better to have a spare day in Cusco instead?
Be prepared for some desperate poverty in Peru; people in mud huts with no water / electricity in the rural areas, and shanty towns on the edges of the cities. However, we found it to be safe & the people friendly.
Beware of the in flight meals on Iberia from Madrid to Lima - take a sandwich instead!!
Help each other out in your group; share things around - after a couple of days you'll all be best of friends. We were sad to leave our group at the end of the holiday; met some great people!
The tipping situation starts to wear a bit thin as the holiday goes on; The tour leader & the porters work really hard for their money; but everyone from bus drivers to local guides to boat drivers are looking for tips - it might only be a 'few quid' but it does mount up & not all foreign tourists are like the rich Americans that locals seem to think!! Having said that, you can pick up goods in the local markets for very good prices with a bit of haggling....
Most of all, just 'got with the flow' and you will really enjoy this holiday. Worth all the effort and early morning starts!