Thanks for your reply!! I am still not very expert yet, I am travelling to eastern Europe in Dec (with group) it is very cold and most likely I will use full auto mode to shoot most of the time cause I do not have the luxury of lot of time at each location. I don't foresee I will be needed to shoot with shutter speed longer than 1/30 sec.
Do you think the 18-270 (without VC) is a good choice?
I am using Nikon D5100 with 18-105 (Kit Lens), I also have a 35mm, 18-55 (Kit Lens). I am still thinking to bring the 35mm with me or not
Travel shots are mostly just snapshots of the things we like and how we want to see it, there's no fault in shooting Auto or Programmed mode and coming back with such images. Unless it's a pure photography trip, yes, you are right, time is limited at each location (better if you are on FnE but group...) so just shoot and enjoy.
Dec would be near the snowing period, my concerns would be more on battery power as well as fogging on the glass when you enter cold->hot. Spare battery, extra memory cards etc.
Shutter speeds will vary during the periods of the day. 1/30 would be feasible if you have a max focal length of 30 (maybe you have more stable hands?). With the mist and the snow, you probably need to increase your ISO/EV to get the desired shutter speed without handshake.
VR here in this case, is quite redundant if you're using a recent body like the 5200 or 6*0 or even D800 which have high-ISO capabilities. The 5100 should still be bearable at ISO 1600, this should suffice for most lighting conditions, even night, step down to f/4 (or 5.6) and just whack ahead with proper breathing techniques.
In Europe, what's your main genre of shooting? Scenery/landscapes? Or street? If scenery is your main core, any WA glass would be more than sufficient: eg: 18-105, 18-35 or even 18-135. The extra reach can be used for street or casual shots. One major pitfall I see on most travellers is to over carry or bring too many to 'capture everything'. I would rather lug along GND filters than an extra glass.
Don't forget, Europe is not like SG, you don't get escalators or lifts often, and the scenic spots are via trekking (unless you opt to pay for transport - if there are, but even if there are, you are mostly still required to do 10-15mins of trekking after alighting). Do you want to carry that much equipment? By the time you reach the spot, you might be even too tired to even press the shutter anymore and busy removing your sweater/fleece to let some air in to cool yourself down.
Safety is also a concern here, if you're bringing a bag that has a camera bag brand shouting loudly in everybody's face, you might consider wanting to change to something like ThinkTank Retrospectives or Urban Disguise to avoid attention. Carry a big back pack is like telling everybody - "HEY! I have equipment here! Come try to rob me!" (at least to my feel). Mostly is safe, but no harm taking more safety into consideration. Have been lucky the past few times in Europe, but no harm being careful as well, especially on trains if you are the kind that easily dozes off.