I am planning a trip starting here in michigan and ending it in greece?

My girlfriend and I are planning a trip to Europe. Leaving from Michigan , going to Ireland, Great Britain, France, Belgium, Germany, Czech Republic, Netherlands, Switzerland, Italy, Greece, Spain, Monaco, Hungary. Hoping to start in June and come back home at the end of August. Not sure if we will be going to Hungary,Switzerland,or Germany. Just looking for some ideas on how to start planning a trip like this. We are going to land in Ireland and leave from Greece or some place closer to the U.S.