Five days in August - Stresa on Lake Maggiore & Torino.
10 days - I’d be checking out any festivals during that time and pick cities around that region.
Some of the August options:
Palio di Siena (Siena, Tuscany): Italy’s most famous historic bareback horse race takes place annually on August 16 in the shell-shaped Piazza del Campo. The festival features four days of pageantry, historical parades, and intense neighborhood rivalries.
(Nationwide): Celebrated on August 15 across the entire country, this national holiday features massive local village feasts, outdoor BBQs, and spectacular midnight firework displays along coastlines (such as the coast near La Spezia and Matera).Major Music & Arts Festivals
(Agrigento, Sicily): Held in early August, this unique boutique music and digital arts festival takes place directly inside the UNESCO World Heritage-listed Valley of the Temples.
Red Valley Festival (Olbia, Sardinia): One of Italy's largest open-air pop, rap, and electronic music events, running mid-August at the Olbia Arena.
Ferrara Buskers Festival (Ferrara, Emilia-Romagna): Late August transforms the historic streets of Ferrara into a spontaneous, global stage for hundreds of international street musicians, circus acts, and performers.