Hello! It sounds like you're planning a magnificent trip to the beautiful Italian cities of Palermo, Catania, and Siracusa. Here are some tips to consider:

Best Time to Visit:
The best time to visit these cities is during spring (April to June) and fall (September and October). The weather during these months is typically mild, and these periods avoid the peak tourist season of summer, offering a more relaxed experience.

Route and Accessibility:
All three cities have airports, with direct flights from many European cities making them easily accessible. For travelling within Sicily, you can use the Trenitalia or Interbus networks. Local buses and taxis are also available in all cities.

Accommodation and Booking:
You'll find a range of accommodations in these cities, from luxury hotels to budget guesthouses and rental apartments. It's best to book in advance, particularly for visits in the peak tourist seasons. Websites like Booking.com, Expedia, and Airbnb can be helpful for this.

Clothing and Essentials:
Pack light, breathable clothing for the daytime and something a bit warmer for the cooler evenings. Comfortable walking shoes are a must. Don't forget your sunglasses, hat, sunscreen, and a water bottle. A small Italian phrasebook could also be useful.

Health and Safety:
Tap water is safe to drink in all these cities. Be mindful of traffic when walking, especially in narrow streets. Also, having travel insurance is highly recommended.

Local Etiquette and Respect:
Italians appreciate polite manners, be sure to say 'Buongiorno' (Good morning) or 'Buonasera' (Good evening) when entering shops or restaurants. It's respectful to dress modestly when visiting religious sites. Tipping is appreciated but not mandatory.