I think you have allotted about the right amount of time all along the way.... true, machu pichu proper is not huge by Texas standards....but after you sit and contemplate it for a while...and take a hike to the top of Wanna Pichu...the peak in the background...you'll enjoy just resting up....altitude, remember, and thinking about how they did it so long ago with the tools they had...for a builder like you, you'll marvel and try to figure it out...The people you run into, for the most part, will be pleasant and informative...much literature available for what to go see...walking shoes a must! Much of the interest is just observing the local houses, culture, how people live, make their living, etc...Remember, a trip like this is subject to surprises re weather, health, delays, transportation, etc.... just part of the adventure....plan in advance things like sunglasses, sunscreen, windbreakers, etc..and you will be fine....many people speak sufficient English for you to get along.... fun to observe facial features...the people you see are true Indians, many pure blood...only a few generations removed from the Incas.
Talk to street venders, wander off the immediate tourist trail in towns.....be aware of safety considerations, but your spidey sense will be true to you...
There are various markets in every location...some more tourist oriented, some more local people oriented....a visit to these will show you many things you would not have thought about before....and, try the local delicacy...the local rodent that many keep as pets...and is also consumed...an experience, but if you like squirrel or rabbit, it'll be kinda familiar. Drink plenty of coca tea!!! I looked for any kind of "kick" to it and didn't find it...but am sure it assisted in avoiding altitude sickness.
Let us know how the trip goes....and, again, i recommend both the catacombs and gold museum in Lima. Remember that you can/should keep your guide book with you.....in a case of lack of communication with a cab driver or whomever, you can pull it out and point to a photo or name....of hotel or tourist destination...and recognition is typically instant....remember, thousands of people make this trek annually....it's good for their economy and they know it.