Great, great question. I would say to encourage them to participate and attend, but let them know NO gifts! This will take some of the pressure off. If possible, encourage folks to arrange something less expensive (i.e. a night out in a city close to everyone, as opposed to flying to Vegas). One cute idea for a less expensive bachelorett or shower is a "panty party." This became HUGE with my group of girlfriends. Everyone brings a pair of cute new panties as a present and you strong them up. The bride has to guess who each pair is from! (guests try to pick a cute pair that is more their style or has a design of some significance to them....i.e. a teacher might find a pair with an apple print...)