It's all up to you and what you like to shoot. You'll hear mention of wide angle lenses, primes, megazooms, portraits, wide zooms, midranges...the photographer's skill, vision, and eye will dictate what lens works best for them.
I would place my argument behind the megazooms as being an 'ideal' lens for Disney for a majority of users, especially beginners. Because of the huge zoom range these lenses offer, they allow the photographer to shoot any subject at any distance with a single lens, no changes required. It helps avoid missing shots because you didn't feel like bringing a bag of extra lenses along, or because you only had the kit lens and couldn't zoom on something far away. It's just overall the most versatile solution, as it can be used in a pinch for scenics, landscapes, portraits, wildlife, architecture, interiors, low light, night...whatever. It won't be the best in any one of those situations, but it can do all of them. Check out any of the lenses that have ranges like 18-200, 18-250, 18-270, etc. These cover from wide angle to big telephoto, and are usually still small enough to wear around a neck or shoulder and not require a tripod.
Personally, I do tend to bring several lenses with me when I'm walking the parks - and I have specialty lenses I like for certain shots (10-24mm wide, 30mm F1.4, etc)...but my 18-250mm tends to be with me virtually always as at least one of the lenses - because of the sheer versatility and range it provides.