As part of your reportoire of lenses for photography, you need to have lenses to cover a wide range of subjects. When you are out covering landscapes, like on most vacations, you need a Wide-angle lens that covers a large vista and then for smaller and smaller area of focus, a progressively longer zoom. Here are some definitions
Focal length less than 21mm – Extreme Wide Angle
21-35 mm – Wide Angle
35-70 mm – Normal
70-135 mm – Medium Telephoto
135-300+mm – Telephoto
With so many zoom lens choices, it is rather easy to get a couple of lenses that cover the range from 17mm-300mm with a mix of two lenses. For an enthusiast photographer, investing in lenses will soon become very expensive and many try to buy just one lens like the Tamron 18-250mm or equivalent ones from Sigma. When a lens covers a long-range, the image quality suffers. No lens will perform optimally at all focus lengths and apertures. Zoom lenses need to incorporate a lot more glass to cover the range and getting them all to work together is the challenge, simplistically speaking.
The Canon ‘L’ series (Nikon has its own series and so do other manufacturers) lenses are what the pros prefer as they provide outstanding image quality (IQ) and quality of construction in the ranges they come with. The pro lenses are usually broken down to shorter focal length ranges such as 17-55, 24-70, 24-105, 70-200, etc. Obviously these lenses cost a lot of money. But if you are willing to invest about $2.5k, then you can consider the 17-55mm lens which isn’t a L series by the way but fits the APS-C format bodies and the 70-200mm F4 L IS lens. The former will cover a wide range of wide-angle shots and the latter is great for tight shots of subjects. The APS-C sensors are smaller in size (25.1 x 16.7mm) than the tradition full frame sensors which are 24x36mm in size. The Full frame sensor mimics the size of the negatives from the good old analog camera times. The advantages of the APS-C bodies are they are smaller and lighter and less expensive. Going back to the lenses, with these two lenses or lenses of these ranges, you will be more than well set for a vacation assuming you want some great photos. You can always get a consumer grade compact cameras with extended zoom ranges such as the Canon SX series, if you have a tight budget; some of these zoom have a real range up to 600mm, but they have their drawbacks.