If you haven’t already I would set the options page to autoload. http://www.advancedcustomfields.com/resources/acf_add_options_page/ This causes WP to cache the values so that extra DB calls are not needed to get them, just in case that’s your concern.
As far as opinion on using a global variable. Global variables, in my opinion, should only be used when there isn’t a better way to do it.
I personally don’t see much difference between the following.
// ACF get_field()
$value = get_field('gallery_wedding','option');
// using a global variable
$value = $weddingopt['gallery_wedding'];
Of the two I would use the first. Why, because at does not depend on a global variable and because it does not create a dependency and require editing the function that creates the global variable every time I add a new field. The global variable option simply increases the work and over-complicates the theme without adding much in the way of a benefit over just using the ACF function where you need the value.
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