Brigham Young declared "This is the place" after seeing the Salt Lake Valley

False, unless you are paraphrasing

The quote that gets attributed to Brigham Young is "It is enough. This is the right place, drive on." However, there is still doubt as to whether he really said this or not. No firsthand account of Young making this statement has ever been recorded. Wilford Woodruff is credited with stating that Young made this quote, but that was in 1880, 33 eyars after the event happened and three years after Young died.

Sources: "111 Days to Zion," by Hal Knight and Dr. Stanley B. Kimball; Deseret News archives; lds.org; "The History of Emigration Canyon," The National Park Service; Mel Bashore and Chad Orton of the LDS Church History Library.