Absolutely, it's great you are planning to explore Szentendre, Kecskemét, and Pécs in Hungary. Here are some travel tips to help plan your journey.

Best Time to Visit:
The best time to visit these Hungarian cities is during the spring months (April to June) and autumn (September to October) when the weather is pleasant.

Route and Accessibility:
Szentendre, Kecskemét and Pécs are easily accessible from Budapest by car, train or bus. Trains and buses run frequently from Budapest to these cities.

Altitude and Acclimatization:
Altitude is not a concern in these cities as they are all at low elevations. However, do take the time to adjust to the new environment and time zone.

Accommodation and Booking:
All three cities offer a variety of accommodations including hotels, guesthouses and Airbnbs. It is recommended to book in advance especially during the peak tourist season.

Clothing and Essentials:
Pack seasonal clothing - light outfits and comfortable shoes for walking in the spring/summer, and warmer attire for autumn/winter. Don't forget your camera to capture the beautiful architecture and natural scenery.

Health and Safety:
Hungary has a good standard of healthcare. In case of emergency, the number for ambulance services is 112. It is always advisable to have travel insurance. Drink bottled water and maintain personal hygiene.

Local Etiquette and Respect:
Hungarians appreciate their customs and traditions being respected. When visiting churches or other religious sites, dress modestly. Learn a few words in Hungarian to impress the locals, they will appreciate your efforts.

Remember to respect the local laws, environment and cultural sensitivities for a pleasant and hassle-free trip.