Ravel had close family links with Switzerland. His father was born in Versoix, near Geneva. His uncle Edouard continued to live in Geneva for most of his life. These antecedents provided some of the context for Stravinsky's much-repeated description of Ravel as "the perfect Swiss watchmaker". Ravel's visits to Switzerland were frequent but more often connected with his family and his health rather than his music.
During the summer of 1906, because of the ill-health of his father and the doctor's recommendations, Ravel went with both of his parents to Hermance on Lake Geneva. They stayed in a hotel for about three months, and Ravel was delighted at least by the landscape and the climate:
"Le lac rappelle étonnamment, parfois, la Méditerranée. Les côtes pas grises, pourtant. Des colorations intenses et paradoxales, des valeurs fausses. Et puis ces barques aux voiles éclatantes, aux formes surannées. Et c'est surtout ce climat doux et d'une pureté surprenante." (Letter to Maurice Delage, in Orenstein  p.87).
Given the family's circumstances, Ravel was anxious about being able to get on with his composing, but after a little while his father's health improved, he himself took delivery of a piano, and he was able to to resume work on his projected opera La Cloche engloutie. (Chalupt  p.56).
Stravinsky had been commissioned by Diaghilev to produce a re-orchestrated version of Mussorgsky's opera Khovanshchina and Ravel agreed to help him with this. In March 1913 he joined Stravinsky in Clarens on Lake Geneva where they stayed in neighbouring hotels. Ravel was at the Hôtel des Crêtes and stayed there until the end of April, working not only on Khovanshchina but also on his own Trois poèmes de Stéphane Mallarmé. At the start of April Ravel was complaining wryly that he had caught laryngitis - in a country where people are sent to be cured of it. (Orenstein  letters 99-101).
At the beginning of April 1914, Ravel was in Geneva for a concert (no further details). (Orenstein  letter 112). This was during a period of several months when he otherwise avoided engagements and retreated to Saint-Jean-de-Luz to make progress on the composition of his Piano trio.
During the summer Ravel had to make an unexpected visit to Geneva, to give support to his uncle Edouard following the death of his wife. (Orenstein  letter 158).
According to a postcard sent to the daughter of Louise Alvar Harding on 31 May, Ravel was then in Switzerland for rest and recuperation of his health (Nichols  p.252).
Ravel spent a week at the end of November on a concert tour in Switzerland, giving preformances in Bern, Basel and Geneva, where he was able to meet one of the few remaining members of his family, his violinist cousin Alfred Perrin. The Geneva concert on 26 November was devoted entirely to Ravel's music, and was organised by the Swiss pianist Franz-Josef Hirt who also participated in the performance. The programme included the Pavane pour une infante défunte, Sonatine, the Trio, Berceuse sur le nom de Gabriel Fauré, and Tzigane. (Orenstein  letter 273 and note).
Ravel became a jury-member of the Société internationale de musique contemporaine (S.I.M.C) which organised presentations of new European and American music, and in early December 1928 his duties took him to Geneva, where he found himself at odds with some of his fellow members such as E.J. Dent (Orenstein  letter 305; Marnat  p.644).
Although he was still recovering from the effects of a taxi accident in October, Ravel went to Basel in December for a concert of his music. (Nichols  p.332).
By 1934 Ravel's health was in serious decline, and in early February he went to the clinic of "Monrepos" at Mont Pèlerin near Vevey for an extended rest-cure. (Marnat  p.670). After a month Ravel was declaring himself refreshed by the mountain air, but although he remained for several more weeks there were no substantial improvements to his condition. (Orenstein  letter 335).