The most versatile lens in my bulging bag is the 18-105. It is not great but is very flexible and has the range that is most useful for me. I got it as a kit with the D90 when it came out 4 years ago and even today some of my favorite portraits and architecture shots have been with it. Technically it is not as good as any other lens in my bag but since it good, not stellar, light, and covers my preferred range it stays with me. If weight was not a problem I would take faster glass, the 70-200 for sure and probably the 24-70 2.8 and 24 1.4.If you are using domestic airlines in India, weight will be a real consideration due to low limits on hand carry baggage.
The test shots were under-exposed so less can be determined by them but the point is, as you have learned, the 18-105 is fine for the application of a travel lens. Consider that lens testing is normally done in highly controlled conditions and on a tripod with remote release. It is likely the 24-120 would beat it under those conditions but remember that what works in crude tests, hand held, with uncontrolled light is actually a better indicator of what you will find by using it in the same uncontrolled conditions doing casual shooting. If the images look better when using your current techniques, it makes little sense to worry about ultimate performance of another lens when it is not going to be used in those optimum conditions while traveling. I would reserve judgement on the 50 1.8D however, when stopped down, it is the best of the lot. When shot wide open, the D version is not very good. But it can capture scenes in low light the others can't. Stopping it down to 2.8-4.8 and it transforms into a super sharp, quality lens. The 18-105 is really good when you can stop it down to 5.6 which will be easy outdoors. I would be happy to take both the 50mm and 18-105 since the little 50 fits in any spare pocket yet opens a lot of options for ambient light shooting that all the others are hampered by. Have a great trip and enjoy the lower weight.... Stan St Petersburg Russia