It is usual practice for conventions to have a number of guests of honour, usually well known creators, most often authors, who the members are interested in seeing. Normally their expenses are paid by the convention, and their names are used in convention advertisintg. There are a few notable conventions that take different approaches, though - notably [Potlatch] which has a book of honour, and [Corflu] which randomly chooses a Guest of Honour from among the attendees at the start of the convention.
The normal practice for Swancons is to have at least one International Guest of Honour, one National Guest of Honour, a Fan Guest of Honour, and a number of Invited Guests.
The selection and confirmation of major guests is one of the most important jobs in the first year of convention organising, and announcement of guests is normally one of the most important parts of a convention launch. Choice of guests is often tied with a conventions theme. If there is one International Guest or one National Guest, that guest is almost always an author. Editors, artists, filmmakers etc may also be great guest choices, but usually not unless there is an author guest in addition.
The choice of International Guest is often a stressful one, as the expense of international air fares etc. is a major budget item, and the choice of guest can influence many aspects of a convention. Publishers are often willing to work with conventions to sponsor a guest (and often arrange other publicity for them). The ongoing goodwill of publishers is important to future conventions, and it is usually a good idea to ask WASFF and experienced convention runners for advice in dealing with them. It is also a good idea to discreetly discuss guest choices with experienced convention runners, ideally get reports from another convention they have attended. Do this before asking them to attend. Once you ask them, there may be some negotiation. Current practice is that conventions pay air fare (usually economy), may pay for a partner to travel with them, pay accomodation for the period of the convention, and may pay a small daily per diem to cover food etc. Typically authors expect something roughly similar to this arrangement. Swancons generally do not pay appearance fees, which generally run to several thousand dollars, and are expected by many actors.
National Guests are typically professional authors resident in a state other than WA (or other creative professionals). They should receive a domestic return airfare, generally economy, and accomodation (and a per diem).
The Fan Guest of Honour is generally a fan with a long history of activity within WA fandom (though someone with a national profile might be regarded as appropriate for a Natcon). It is regarded as an honour. The extent and way in which fan guests contribute to the program varies by fan guest, and they should be encouraged to contribute in a way that suits them and highlights their contribution. It is a good idea for committees that are relatively new to fandom to consult with more experienced fans about a fan guest choice.
A regular Swancon feature is Invited Guests. An invited guest is a guest who is not provided with as much support by the convention, typically given a free membership. Swancons often have several Invited Guests.
Over the years various other categories of guests have been created, often on an ad hoc basis. A few conventions had a Dead Guest of Honour, a dead author that was honoured by a number of program items about them, and perhaps other aspects of the convention (for example, Jules Verne was one Dead Guest of Honour, and a local fan played them in costume at some convention events). One convention had a Gratuitous Interstate Guest of Honour. There have been other special types of guest.