Sure, travelling across Munich, Gelsenkirchen, and Bayreuth is a great way to experience German culture. Here are some travel tips for you:

Best Time to Visit:
The best time to visit these German cities is between May and September when the weather is pleasant and ideal for sightseeing. For the beer enthusiasts, late September and early October is the time for Oktoberfest in Munich.

Route and Accessibility:
All three cities have good connectivity by road and rail. Munich has a well-connected airport with flights from all over the world. From Munich, you can catch a train or a bus to Gelsenkirchen and Bayreuth.

Altitude and Acclimatization:
These cities are at low altitudes, so altitude sickness is not an issue.

Accommodation and Booking:
There are plentiful options for accommodation in all these cities ranging from luxury hotels to budget BnBs. It's recommended to book your stay in advance, especially if you're visiting Munich during Oktoberfest.

Clothing and Essentials:
Pack clothing according to the season of visit. Carry a good pair of walking shoes as these cities are best explored on foot. Also, remember to pack a universal adapter for your electronics.

Health and Safety:
Remember to take out travel insurance. Tap water in Germany is safe to drink. Follow local COVID-19 guidelines during your travel and stay.

Local Etiquette and Respect:
Germans respect punctuality, so be on time for any appointments. Remember to tip in restaurants, 10-15% of the bill is usual. When in public places, keep your voice low as Germans are quite appreciative of their quietness. Try to learn a few common phrases in German, it's appreciated.