Nope, no shared bathrooms on this tour. I HAVE had a shared bathroom on the 21 Day Best of Europe but not on GAS. I had single supplements on each one.
Here's where to look, and I am giving you the example of the tour where I DID share a bathroom.
Go to the Tour page:
Scroll down to Physical Demands:
Number 5. Be content with the possibility of sharing bathroom facilities at one hotel during this tour. (Sorry I had to type Number 5 - if I just put 5 down it keeps changing it to a 1 and if I use the # before it makes it all big caps)
For the GAS tour the shared bathroom is not listed:
1. Carry/roll your luggage over uneven pavement (possibly several blocks) and up stairways to reach your hotel, then up several flights of stairs to reach your room.
2. Be on your feet, walking and standing for up to three hours, indoors and outdoors, in all weather conditions.
3. Sleep with street noise and no (or weak) air conditioning.
4. After orientation and transportation lessons, be able to navigate towns and cities on your own.
5. Adjust to constant Alpine weather changes that can interfere with sightseeing.
6. Handle steep walks and long castle stair climbs at Burg Eltz, Neuschwanstein, and Trümmelbach Falls.
I think the one other tour where there is a shared bathroom is one of the ones with Scandinavian stops.