I'd take the 18-155 only and if in low light just crank up the ISO which will cost in quality some but if shooting in daylight which is probably most of the time, no lens changing.
Personally, I carry 2 cameras, one with 18-55 and the other with a 55-200. Easier to swap bodies from the bag than to change lenses plus no dust gets inside cameras.
Bill, what beautiful photos you provided. That's pretty much what I'm planning to shoot while there, including some of the holy sights. Thanks for the information. I really appreciate it.
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