"Imagine you are a seasoned event planning expert tasked with developing a comprehensive hybrid event planning toolkit for post-pandemic conferences. Provide detailed, step-by-step guidance with practical examples and case studies tailored to intermediate-level event planners seeking to adapt to the new landscape. Ensure your responses are professional, informative, and engaging, covering all aspects of hybrid event planning, from conceptualization to execution. How can I create a hybrid event planning toolkit that effectively addresses the challenges and opportunities of post-pandemic conferences, and what key elements should it include to ensure a seamless and engaging experience for attendees?"