One thing you should consider when ordering tickets for events outside of the trip itinerary is "Will you have sufficient time to see what you want to see?" If your trip does not allow for sufficient time, you may be disappointed. A second thing you should consider is: "How will you get to where you have to go from where your tour will be?" Most cities have good public transportation, and if you're not afraid to use it, will be a quick and inexpensive way for you to get there. Of course, you can always opt for the more expensive taxis if you're not that proficient in using public transportation. A final thing you should consider is, "Will you have to wait on line if you don't book in advance, or will you not be able to get in at all? When we visited the van Gogh museum in Amsterdam on our trip to see the tulips last year, the lines were humongous if you didn't have a ticket in advance. When we went to the Anne Frank Haus, if you didn't have a ticket in advance, you didn't get in, as they give you a ticket for a specific date and time. We were the only ones on our trip to see the Anne Frank Haus because of this. The lines were simply too long for the rest of our group to wait on, as there were other trip activities they would have to miss.
Your program director may be able to purchase tickets for a group, if there are no constraints, but we would suggest that you depend on that. We suggest you check the web sites for all the venues you want to see to see what the requirements are, and ask others who have been to those venues what the circumstances of wait time is and then make your decision. Remember that if others of your group don't want to do what you're doing, your PD might not purchase group tickets, but he/she may make a call for you. Our advice is to make certain you get what you want and do it yourself. The alternative is that you may not see what you want to see.