Believe me, even if you only need them once a year you'll be glad you brought them. Never expect much. They are the forgotten technical element of most shows. Clubs will have this under control, organizations seldom do. You only exist on paper to most of the media and presentation tells it all.
Papers generally hate that kind of visual busy-ness.
Press people love it, promoters love it. It'll get you press, it'll get you work. Provide your own posters, if you can afford it. That way you know how you're being presented and the promoter doesn't have to invest the money in designing and printing one up for you. Make it attractive and generic with a big blank area to fill in the info on specific gigs.