You should choose a comfortable size for your expected attendance. While you don't want an over-crowded event, it's also uncomfortable when a small group meets in a large venue. The empty space is disheartening, and can even create a false impression of poor attendance. Atmosphere can be important, too. Some venues are visually neutral, while others make a strong visual impression.
Outdoor patios can be particularly flexible.
Lights, banners, canopies and potted plants can create a colorful fiesta or a dignified award presentation. Venues also offer the possibility of varying the presentation format. When you've developed your agenda or event schedule, consider what services and equipment are implied. Sometimes a hospitality area, with coffee and pastries, can be a lifesaver for early arrivals or volunteers. It's easy to forget details when you're planning a large event.