Hello! That sounds like an exciting adventure you are planning to Argentina's popular destinations - Puerto Madryn, El Calafate, and Ushuaia. Here are some travel tips for you:

Best Time to Visit:
The best time to visit Puerto Madryn is between June and December, which is the whale watching season. As for El Calafate, it's best visited from November till late February, when weather conditions are ideal for walking on the Perito Moreno Glacier. Lastly, Ushuaia can be visited year-round but it's especially beautiful during the Southern Hemisphere’s summer (December through March).

Route and Accessibility:
Puerto Madryn is accessible by plane, with daily flights arriving from Buenos Aires. El Calafate also has an airport serviced by numerous flights from Buenos Aires. The final leg of your journey, Ushuaia, can be reached by bus from El Calafate or plane from Buenos Aires. There are also flights available from El Calafate.

Accommodation and Booking:
You have numerous choices for accommodation in these cities ranging from hostels to luxury hotels. Booking can be done online on websites such as Booking.com, Airbnb, or through a local travel agency. It's advised to book in advance especially during the peak season.

Clothing and Essentials:
Due to the variable climate, pack layers of clothing including warm jackets, hats, gloves for the cold nights, and lighter attire for warmer days. Other essentials include a good pair of walking shoes, sunscreen, sunglasses, and a hat.

Health and Safety:
No specific vaccinations are necessary for these locations. However, it is recommended to have up-to-date routine vaccines, such as tetanus-diphtheria. If you're going for any adventurous activities, make sure you have a good travel insurance. Always take precaution against petty crime and keep your belongings secure.

Local Etiquette and Respect:
Argentine people are friendly and welcoming. Proper greetings are important and it's common to greet with a kiss on the cheek. Local customs should be respected and it's imperative to follow guidelines while visiting any nature reserves.