Simplified overviews enable novices to more easily begin data analysis and enable experts to see common and surprising patterns. Simplified overviews have been used in research and commercial software for multi-variate data by choosing two dimensions to show on a scatterplot. We bring this idea to temporal event sequences, by facilitating the selection of two event categories. This simple strategy was inspired by observations of our case study partners and appreciated by pilot study users. The design was extended to provide six metrics for selecting categories that simplified the overview to display. To address the need of expert users, we also present simplified overviews using a lower triangular matrix of small overviews with all pairs of event categories. Along with single event category overviews shown on the diagonal they provide a revealing overview of the dataset. We believe these simplified overviews help novice and expert analysts to more rapidly and successfully extract insights. The design is implemented in the EventFlow software and refined based on two usability studies with 5 and 6 users. As a result of our work, guidelines for the design of simplified overviews are proposed.