D800 w/ 24-70 f2.8 or 50 f1.4 for Disneyland and Universal Studios Hollywood?

A no brainer in my books a little extra weight will not make that big a difference but there will be shots you can't step back to take that the 24-70 will make easy. Most of the time in the situation you're talking about 1.4 will make no difference but having the versatility of the 24-70 will.

Have a great holiday and capture some wonderful memories