Could I just mention that the dreaded high-vis vests, as mentioned above for photographer/enthusiasts, can be confusing for incoming aircraft when one is conditioned (vaguely) to expect any marshallers to be wearing same? As one lands, there is often a crowd of photographers and ones concerns are to taxy as required, get to the parking and not bump into anyone, not necessarily in that order. Trying to sort out marshallers from others is much easier if only those who need them are wearing them.
Not knowing the arrangements yet to be made for parking, I may well be out of order, but I know this has been an issue at some popular places where the number of people wearing the day-glo 'authority' all but equalled the number of aircraft. Arriving aeroplane drivers need to know that the person in the yuk-coloured vest waving his arms in helpful fashion is the marshaller, not an enthusiast waving to his mate. Should be obvious, you say, but when there's a sea of spotters, it isn't necessarily so. Personally, I'd like to see a different badge for those designated safe enthusiasts.