At some point after his arrival in Michigan, Gardiner visited Mackinac Island; the exact date is not known. His earliest Mackinac images date to 1896, the year he opened his gallery in the studio formerly occupied by the Foley Brothers in the Marquette Building at corner of Fort and Main Streets. The Petoskey Daily Resorter announced he was "prepared to do all work and in the latest styles." Within a few years he moved down the street to the second floor of Fenton's Bazaar, where he would remain for the remainder of his career. Gardiner was drawn to the resort life, for at about the same time he came to Mackinac Island he began spending his winters in Daytona, Florida. He may have been plying his trade there as early as 1894. In 1901 he and Louise opened "Gardiner's Gift and Art Shop" in downtown Daytona. Gardiner ran his studio in the back of the building, while Louise operated the store at the front. Thus, at the turn of the twentieth century the course of Gardiner's life was set, with a summer studio on Mackinac Island and a winter one in Daytona. Daytona appears to have been his place of primary residence after 1905 (he remained in the Detroit residential listings until 1905), where he was active in civic affairs. He eventually purchased the building he was renting along with adjacent property to construct the Gardiner Building, a retail and office block. Along with his son Marshall, he was involved in other real estate ventures including purchasing the Colony House (Palmetto) Hotel. The hotel burned in 1922 and the Gardiners replaced it with apartments and two residences, one for himself and Louise and the other for H. Marshall and his family. H. Marshall Gardiner the son of William H. Gardiner, was also a photographer and began work in Bermuda in the early twentieth century and in 1910 established a summer shop in Nantucket, Massachusetts.