First, I see you've only posted twice on the Rootsweb Message system. When you post, it is very helpful to post some criteria information about the persons you seek. The date of birth of William and Grace might help locate them elsewhere or at least get a background of their movements. When I do research, I try to find if the poster had a posted family tree on the person, if not, I try to get a background of them.
--The Utah Pioneers Memorial Gallery Index Cards:
William Rowsell, born 1 Nov 1843, died 2 July 1916, born in Crewkerne, Somerset, England.
Grace Lye, born 25 April 1852 in Haazelberg, Somerset, England, died 21 April 1931.
Donor listed as a Jenill Rowsell Ivory.
The 1900 Census of West Jordan, Salt Lake Co, Utah
William, born Nov 1842 in England, immigrated 1870/Naturalized, farmer, married 36 years (1863/1864),
Grace, April 1853 in England, immigrated 1873, mother of 12/10 living.
--If they had been married 36 years, Grace would have been about 10/11 when they married. Eliza, daughter was born June 1883 in England, so if correct, this family (or just Grace) had either returned to England from the US, or they hadn't immigrated in 1870 and 1873. So, while the census does have a lot of errors, there might have been a break in residency. Charles, son, was born March 1885 in Utah. Of the 12 births, only five were shown in this 1900 census.
I find 8 posted family trees on William and Grace. One, "possibly" answers the length of marriage question. It shows William was first married to a Marcy Webber in 1864 in England, he married Grace Lye in 1875 in Salt Lake City. Frederik (as spelled), second son, was born Jan 1877 in Richmond. Daughter Rosina was born June 1877 in Somerset, England (while this date and Fred's birth date are inconsistent with reality). Eliza, as identified in England. Then Walter in 1879 in Richmond.
--The one problem with posted family trees is ERROR's. A LOT of them have incorrect data. So be very careful of using them without proper source material (actual documented records supporting the information).
The problem finding them in the 1880 census, different spelling of last name; the enumerator didn't find them at all, or they were not at home during the enumeration period. The problem with the 1890 census... Most of the census records were burned, there are no indicated records for census enumerations for Utah.
I checked the Bureau of Land Management land patent database for the last name and found no records. This database contains those records for federal land being sold or provided under the Homestead Act or other Congressional Land acts:http://www.glorecords.blm.gov/search/default.aspx#searchTabI...
I seriously doubt there were City Directories published for Richmond in those years.
Since you live in Richmond, I'd suggest visiting the local county assessor's office and ask about their historic records. Usually the OLD records were hand printed in the "Big Books," large red volumes about 18" x 24" in size. If they do not have such old records, they could advise on potential locations. Property records of such nature might also be found in the State Archives.