I went to Messina at the end of August last year, and I honestly enjoyed it. I went for 4 nights, and I found it to be a vibrant and busy city, but not crowded. It was very clean and more appealing than Catania. I would aim to stay there between Wednesday and Saturday. Cruise ships are frequent and make the city feel even more lively. There are lots of bars and restaurants to indulge in. There is a lot to do, and you can see it all in two days without rushing. I would highly recommend using Messina as a base, as you can travel to lots of fantastic places (Taormina, Cefalu, Lipari, Tropea, Milazzo and Calabria. I will make a list of destinations nearby and locations in Messina to visit below. Go to the main cathedral at 11:45 am, as at 12 pm there is a show on the clock tower, which is quite cool and unique.
Messina. Main cathedral, Tempio di Cristo Re and Santuario Parrocchia S.Maria Di Montalto (both lovely churches with stunning panoramic views. Orion fountain and Fontana di Nettuno (both 600 years old), Statua dell'Immacolata Concezione (go in the evening for a cool view of the clock tower and fountain. Santuario Parrocchia di Santa Maria del Carmine and Chiesa Santissima Annunziata dei Catalani (lovely historic churches). Try watching ACR Messina play at Franco Scoglio Stadium. And of course Stele della Madonna della Lettera (one of the most iconic statues. For shopping, go to Tarigghia Gigante, where you will find shops like Zara, Pandora, Calzedonia, H&M, all amongst lots of other shops and boutiques. Messina is a great city for food, and the nightlife is great as there is the University of Messina.
NEARBY TRIPS (MOST CONVENIENT FROM MESSINA) Taormina (45min), Cefalu (1hr 40- 2hr) Lipari (2hr 10-30 ferry), Tropea (90min car or 2hr 30 train), Catania (1hr to 1hr 20) Syracuse (1hr 40 car or 2hr 30 train) Reggio Calabria, Milazzo & Barcellona Pozzo di Gotto (30min).
Go for a lovely hike in the mountains nearby. Il Chiosco dei Colli is a place for some food, but hike around this area. There are a few markets in the city for fresh food.
Messina is an extremely underrated city. It has so much to offer, but it always gets forgotten. There is so much history in this city, it's absurd that it isn't more popular. It's easy to get to from Reggio Calabria airport, Catania Airport, or a train from Rome & Naples. I WOULD RECOMMEND STAYING IN MESSINA FOR 7-12 DAYS FOR ENOUGH TIME TO SEE EVERYTHING IN THE CITY AND SURROUNDINGS WITHOUT RUSHING.
Note, I didn't get to visit Lipari, unfortunately, because I didn't plan for long enough, and I stayed in Cefalu as I met a friend who lives there.