After a week of previews, the central exhibition of the 61st Venice Biennale , “In Minor Keys,” opens to the public on Saturday, May 9, accompanied by scores of exhibitions all over the floating city. A very few people will see every show , but for most, partaking of the festivities requires tough choices. Even on a long vacation in the Most Serene Public, there is time for only so many stops. Below, Artnet’s writers share some of their favorites, from the national pavilions of the Giardini to affairs that are much further afield. “Ei Arakawa-Nash: Grass Babies, Moon Babies” at the Japan Pavilion, Giardini, through November 22 Artist Ei Arakawa-Nash in Japan’s pavilion. Photo by Katya Kazakina Babies to the rescue! The Japan Pavilion was an oasis of calm amidst all the protests erupting on the grounds of Giardini and Arsenale this week. Filled with gentle music and baby cooing sounds, it greets visitors with milk bottles that adorn its entrance.…