I helped arrange an AT trip to Majorca when i was in the factory.
Decide what it is you want to do.
Decide on how much you are willing to spend (don't assume everyone has the same level of disposable income as you).
Do a quick search for accom on internet
Do a quick search for travel costs, (and any insurance costs etc)
Set a date
Split the planning/organisation down into manageable tasks, and delegate. It gets everyone involved.