I just finished adding the areas for all the rest areas and travel plazas in California from the caltrans website. The data was in points, and I added the area for each item based on bing imagery. They have some good data sets that might be useful for reference. One other one that I have started adding is the caltrans maintenance station area. There are about 400 so if anyone wants to help add the areas especially for southern cal let me know and I can send you the josm file for the area you are interestedin adding.