Foot support systems include sole structures, portions of sole structures, drop-in midsole components, insertable sole components (e.g., midsoles or insoles), or the like. The foot support systems may include a foam base member (e.g., made from a relatively thick foam material) and at least one fluid-filled bladder. The fluid-filled bladder(s) may include one or more interior fluid chambers. When multiple interior fluid chambers are present, they may be at substantially the same or different pressures. Additional aspects of this technology relate to articles of footwear that include such foot support systems, such as slides, sandals, and / or other types of footwear.