some of the answers you've received are in reaction to your using txtspk in your posts.
In general, on this forum, you're probably more likely to receive helpful replies to your questions if you write the words out in full.
There are several ways for you to cut the costs of your trip:
1. Join couchsurfing, and make your profile interesting (to do this, read a lot of other profiles to see how they are done), and then you can ask hosts if you can stay for free on at least some of the nights on your journey.
2. Have a good look at airbnb hosts, which can be considerably cheaper than Hotels
3. Consider Youth Hostels. They are not only for youth, and some of them have very nice rooms, but cheaper than hotels.
4. In Germany, the national railways offers a so-called "Länderticket". This entitles one or more persons to travel on all the non-intercity, non-express trains within one "Bundesland" (province) of Germany, for one full day. Those local trains are, of course, slower, but even so, one can have a great excursion, perhaps by going somewhere together on one day, sleeping over there for two nights (one day to actually look at the place you've reached) and then another such day-ticket to travel back home (assuming your base is in Zurich). https://www.bahn.de/p_en/view/offers...d-ticket.shtml https://www.bahn.de/p_en/view/offers...overview.shtml
5. Some museums or tourist attractions (e.g. the Eiffel Tower in Paris) have online booking systems, where one can buy tickets in advance. Sometimes these tickets are cheaper than paying once you are there. In any event they save you the time of standing in the queues. Often, however, the ticket assigns you a specific time slot, so it is worth booking in advance only if you can be sure to get the people there on time.
About expectation management:
With so many people in the group, one idea I've found helpful is to ask each person
a) what would you like to do or see, just once on this trip, that would make the whole experience worthwhile for you, what would make it special or wonderful, what would fulfil a dream for you? Be careful, when asking this, to explain that you are not sure whether or not you'll be able to make anyone's Special Thing happen, and that therefore a list of three things from each person would be helpful.
b) what do you imagine would be just totally awful, what would spoil the whole journey for you, what do you definitely not want to experience at all, that could make you wish you had never set out on this trip? Then try very hard to plan to avoid those things.
Bear in mind that sometimes it can be useful to split the group for a day or two, or several times for half a day, because anyone from anywhere can get on one's nerves after a while. Visualize all these people in their home environment: would they be happy to be together day and night for two weeks? When they live at home, at what point do they tend to split up, and do something else, for themselves, and then return again? In particular, if the physical abilities are very divergent, it can be frustrating: the slow or frail can end up becoming exhausted trying to keep up while the young and fit don't want to be hanging around waiting all the time. Let the young folk dance and run. The same is true if the people's basic nutrition and interests don't match, e.g. museums, outdoor activities, shopping... Being apart for some of the time can make the time together easier and happier.