You're interested in omnibidding, but realize that some categories are offline only. Which of these omnibidding setups is optimal?

Campaign-level omnibidding is optimal because it allows you to segment your campaigns based on product categories, enabling you to apply omnibidding strategies only to those categories that have an online presence. For offline-only categories, you can use traditional bidding strategies within separate campaigns. This granular control at the campaign level prevents omnibidding from being applied inappropriately to products that cannot be purchased online, ensuring efficient budget allocation and performance. Ad group level is too granular for this kind of strategic segmentation, while account and ad levels lack the necessary control to differentiate between online and offline categories effectively.