Going east on 42nd St. from Fifth Ave. (the middle of the street), you have Madison, Park, Lexington, Third, Second, First, and the East River.
Grand Central is between Madison (actually Vanderbilt, a mini-street south of Park) and Lexington, the Chrysler Bldg is between Lex & Third, the Daily News (Planet) Bldg is between Third and Second.
The UN Building is closer to the river and a couple of blocks up.