On a first time cruise to Europe, even after doing all the leg work you'll want to have very careful planning. Keep a very close eye on the time and time frames of any tours or visits on your own that you plan. Leave plenty of time at the end of each port day to make your last stops close to the ship instead of working your way away from the ports. You do not want to be many miles from the ship and have something go wrong and no time to find alternative transportation options. A tour bus flat or breakdown, a long line at the last stop that you really wanted to see and a few dozen other unexpected things can change your plans and you have to be willing to drop that last, must see, if time gets away from you. This is not so much of a factor if you do cruiseline tours but is very much a factor if you go off on your own or even with an outside tour. Don't cut things close. You probably don't speak the language and that can complicate issues that can develop with transportation.