Service robots have the potential of improving the quality of life and assist with people's daily activities. Such robots must be capable of performing multiple tasks and schedule them appropriately while interacting with people over long periods of time. In addition, the robots have to deal with potentially unknown users, handle requests that may have (critical) time constraints and perform in dynamic environments while effectively addressing all the requests received. This paper demonstrates the use of the Auction Behavior-Based Robotic Architecture (ABBRA) in order to develop effective service robots. The proposed approach has the following contributions: i) it enables long-term operation of robots and their interaction with known and unknown users, ii) it handles multiple user requests while dealing with potentially critical time constraints, iii) it provides a reusable interface based on ABBRA, which can run on multiple platforms and iv) it supports flexible interactive capabilities such as requesting that the user wait in order to complete a time sensitive task. The proposed system was demonstrated on two physical robotic platforms: the Adept Mobile's Pioneer 3Dx TM and the Segway RMP®.