We use bookourplane .com. It's free and is quite capable. As administrator, I can manage our aircraft, our members, control the schedule, and maintain files of .pdf documents. I can also post messages to all our members.
Only 1reservation that includes a holiday is permitted at any given time. Only 2 that include a Saturday or Sunday, & only 3 that include a weekday. Multi-day trips are normally subject to a two-hour per day minimum.