u can always get a backpack size tripod for emergency uses such as low light and night photography. Many of the european cities have dazzling night views especially the very artistic and culture rich ones such as venice, Zurich, Lucerne, Milan, Munich, London, Madrid, Helsinki etc. U will only blame yourself for bringing less and having no time to shoot all of them...that's why I always prefer to travel by myself instead of travelling in a group.
If u are travelling light and tight, u can always get a photovest to help u organise, forget about bringing your clumzy camera bags along, they shout tourists and u irritate your tour mates because they know u gonna take a long time. I travel in tour groups whenever I bring my parents aboard and the most irritating people are the amateur photogs that don't organise their shooting gears and end up delaying the whole tour group.
Get a quick to setup monopod, I'm using a neotec after fumbling over many years with a gitzo. They work great in a matter of seconds. And if u shoot a lot with assisted flash, get your batteries handy. That's about all u need to experience.
PS : if u are bigger size, angmoh tour buses can wear photovest, if u are big size and in small tour buses, then u have to downsize all your zooms and your bodies liao because your photovest may not allow u to sit comfortably.