You can access both lounges on the same day. Since you're arriving from a ''safe'' country (US) you don't have to reclear security and you can follow signs for ABCD piers. The KLM Schengen Lounge is one level up from the main concourse After passing border controls take the escalator/stairs and follow signs for lounge 25. Be aware of possible long lines at border control when holding a non-EU/EER passport.