Eight and one half by eleven inches is considered the 'standard' size for stationery. Because it is standard it is preferred. When used for a newsletter, it easily accommodates other items such as reports, letters and brochures which have previously been printed or typed on other sheets of standard size paper. Some chapters are using the 11 X 17" size paper and folding it giving four sides on one sheet of paper.
Some chapters which use this standard size prefer to fold it in half to create an 8-1/2 x 5-1/2" format. Some chapters have published their newsletters on 'legal' size paper (8-1/2 x 14"). They soon discover that the three extra inches bring with them a great many more problems than advantages. The longer size creates its own unique filing and mailing problems. It does not lend itself easily to the inclusion of items printed on standard stationery and, if the chapter decides to have a legal size newsletter bound as a permanent history of chapter activities, it soon discovers that the costs may be prohibitive.
If you are operating on a limited budget and concerned primarily with communication rather than physical size or beauty, standard size paper is easiest, best and least expensive.