This is a subject I cover at least once a year.
If you own a digital camera that allows the addition of a flash unit (sometimes referred to as a Speedlight), I highly recommend investing the money and time into getting and learning how to use it. Like tripods, I know people do not like to carry a lot of equipment into a Disney park but, in my opinion, a flash unit is a must.
For example, I took this photo of a family member without a flash. I knew as soon as I did it would be a dull and murky one.

Could I work on it in post? Sure, but it would never be as sharp or render correctly.
I told him to hold that pose and quickly placed my Nikon SB-700 Speedlight onto my Nikon D750 digital SLR camera and re-took the photo.

Much, much better. The advantages of a flash for both indoor and outdoor (see Fill Light) photography can not be overstated.
For more information on using Bounce Flash, review these past posts: Bounce Flash and More Bouncing Light.
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Just as important, learn and follow the rules as to where flash can be used. Using flash can improve your photos, but familiarize yourself with the settings to be able to turn it off in restricted areas…like dark rides!
Well said, John. It gets old on dark rides when this happens or I see people taking a night photo of Cinderella Castle with the flash on. Flash is very limited to how far it is useful.