BB
All the different GPS have a search function. You have to specify an area to search if it is not where you are; typically it will ask, 'Search around here?'. If not around where you are, specify a place, then look under 'Transport', sub-category 'Airport' and it will list whatever is nearest. does the same with train stations, ferry terminals (Yes, even the ones along Klong Pong - aka Klong Saen Saeb, the inner Bangkok ferry).
Each different GPS unit has slightly different programming, play around with it until you're familiar with the functions. Just make sure you have the latest update and you won't get too lost.
Some, like Garmin, lock you out when navigating, but others may just issue a warning not to do so, but still allow manual inputs.