For a great view of the city (especially at night) go to the top of the Eiffel Tower at Paris. It also offers a great vantage point for viewing the water show at the Bellagio.
Take 50€ and put it somewhere safe, your suitcase, your travel documents, wherever. This way you'll have it just in case.
A hike to the top of Yosemite Falls is among the best the park has to offer.