Hello! That sounds like an exciting trip. I'm happy to provide some travel tips for your visit to Panama City, Colón, and David.

Best Time to Visit:
The best time to visit Panama City, Colón, and David is during the dry season, between mid-December and mid-April, when you can make the most of the outdoor activities and clear skies. However, these are also the peak tourist months so expect more crowds.

Route and Accessibility:
Panama City's Tocumen International Airport is the country's main gateway. From there, you can reach Colón by bus or car in about an hour. To travel to David, you may take a domestic flight or a bus, which can take around 6-8 hours.

Accommodation and Booking:
There are wide options to suit budgets for accommodation: from luxury hotels to budget hostels. It's recommended to book your accommodations in advance, especially during the peak tourist season. You might find cheaper rates on the outskirts of the city if you're willing to travel a bit for attractions.

Clothing and Essentials:
Lightweight, breathable clothing is essential due to the tropical climate. Don't forget to carry a waterproof jacket or poncho as sudden showers can happen. Sunscreen and insect repellent are important too. Comfortable pair of shoes will be useful if you plan on doing a lot of walking or hiking.

Health and Safety:
Make sure to have comprehensive travel insurance. Always drink bottled water, as the tap water in some areas might not be safe. Try to avoid mosquito bites to prevent dengue or zika virus. In terms of safety, it's generally safe in these cities but always be cautious of your surroundings and avoid displaying expensive items.

Local Etiquette and Respect:
Panamanians are generally friendly and respectful. Dress modestly, particularly in rural areas and when visiting religious sites. It's polite to greet people with a handshake. Tipping is customary in restaurants and hotels.