1.  Marriage Record:

2.  1890 Census:  the 1890 Census Population Schedules were destroyed.

3.  1900 Census Every-Name-Index/Images (online at Ancestry.com, Image #25 of 31):  1757 Stout Street, Denver City (Ward 3), Eighth Precinct, Arapahoe [now Denver] Co., CO, Roll T623_117, p. 172A, SN 13, SD 24, ED 20, enumerated 13 Jun 1900, official enumeration date 1 Jun 1900 (extracted by Diana Gale Matthiesen):

1900:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
		1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	19	20	21	22	23	24	25	27
*	1737	159	332	Straub Louis	Head	W	M	Feb 1869	31	M	10			Kansas	France	France	Hotel Proprietor	0		Y	Y	Y	R	H
				______ Rose M	Wife	W	F	May 1876	24	M	10	2	1	Kansas	Ireland	Kansas				Y	Y	Y
				______ Tommie	Son	W	M	Oct 1893	6	S				Colorado	Kansas	Kansas			9	Y	Y	Y
*Stout Street

Plus many staff and guests.

4.  1910 Census Index/Images (online at Ancestry.com, Image #11 of 23):  1106 17th Street, Denver City (Ward 3), Precinct 2, Denver Co., CO, Roll T624_114 (Part 2), p. 166A, SN 6A, SD 1, ED 58, enumerated 26 Apr 1910, official enumeration date 15 Apr 1910 (extracted by Diana Gale Matthiesen):

1910:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
		1	2	3	4	5	6	7	8	9	10	11	12	13	14	17	18	19	20	23	24	25	26	28
*	1106	58	54	Straub Louis	Head	M	W	41	M1	20			Kansas	Germany	Germ Ger	Eng	Prop	Hotel	Emp	Y	Y		O	H
				______ Rose May	Wife	F	W	33	M1	20	1	1	Colorado	Ireland	Ohio	Eng	None			Y	Y
				______ Thomas	Son	M	W	16	S				Colorado	Kansas	Colorado	Eng	None			Y	Y	Y
*17 Street

Plus staff and guests.

5.  1920

6.  1930

7.  Wilbur Fisk Stone, ed.  1918.  History of Colorado.  S. J. Clarke Publ. Co. (online in the Archives of the Denver County COGenWeb site).  Vol. II, pp. 45-46:

LOUIS STRAUB. One of the most prominent and popular figures in hotel circles in the west is Louis Straub, the proprietor and manager of Hotel Midland and also of the Great Northern Hotel of Denver.  He is thoroughly familiar with everything required in modern hotel management and displays a most progressive spirit in the conduct of his interests.  His life is an expression of that enterprise which has been the dominant factor in the rapid and substantial upbuilding of the west.  He was born in Wathena, Kansas, February 25, 1869, a son of Alexander and Katherine (Frein) Straub.  The father was an engineer and has now passed away.  In the family were four sons: E. G., Frank, Charles and Louis. The last named, the youngest in the family, was educated in the public schools of St. Joseph, Missouri, and has been a resident of Denver since 1885.  Here he resumed his education, attending the Arapahoe street school for two years.  After his textbooks were put aside he turned his attention to the hotel business and found in it a field of labor that has proven most congenial and also profitable.  For a time he was hotel clerk for others, being connected with the Palmer House in an early day.  He has engaged in business on his own account, however, since 1888 and has been at his present location for sixteen years.  He has been identified with the Great Northern Hotel for a quarter of a century and owns and manages both the Great Northern Hotel and Hotel Midland.  The former is located at 1612 Larimer street and the latter at the corner of Seventeenth and Arapahoe streets.  Both are popular hostelries, liberally patronized, being conducted according to most progressive methods of modern hotel keeping. In 1890 Mr. Straub was united in marriage to Miss Rosie Corbett, a native of Denver, and they have one son, Thomas P., twenty-four years of age, who was associated with his father in the hotel business.  He enlisted, June 15, 1918, in the United States Aviation service, and is now at the Officers' Training Camp, Fort Collins.  Fraternally Mr. Straub is an Elk, holding membership with Lodge No. 17, at Denver.  He was appointed by Mayor Arnold in 1913 to the position of alderman of the third ward and in May, 1917, was elected a member of the new city council from the seventh district.  He is an independent democrat in politics, for while he usually votes with the party, he does not consider himself bound by party ties.  He is a man of fine personal appearance, affable and genial in manner, forceful and resourceful in business, and is known as one of the leading and popular hotel men of the west.  His entire life has been devoted to this business and he has studied everything bearing upon success in hotel management.  His plans are always carefully defined and promptly executed and he has put forth every effort to please, recognizing that satisfied patrons are the best advertisement.