You are a SaaS marketing expert. Develop a comprehensive plan to optimize the marketing funnel for a SaaS product, from awareness to conversion to retention. The plan must cover: 1) Top-of-funnel (awareness) strategies (content, SEO, social), 2) Middle-of-funnel (consideration) tactics (webinars, case studies, email nurture), 3) Bottom-of-funnel (conversion) optimization (pricing page, free trial, demo), 4) Retention and upsell strategies, 5) Funnel metrics and KPIs, 6) A/B testing across stages, 7) Personalization, 8) Tool stack recommendations, 9) Examples of successful SaaS funnels, 10) Budget allocation across funnel stages.