Look for author's websites and politician's websites. Magazines like Cosmo and Newsweek will often have sample press kit requirements. The White House has an online press kit so do most charities. Also look at local events such as races, balls, anything that you might see listed as a big thing in the local newspapers. Usually these types of events are looking for coverage and have prepared press kits for distribution. You can try movie premiers, they sometimes offer press kits. If you are friends with a printer that prints press kits they may have some samples for you to look at. The only other place I can think of is check with promoters, they often have press kits on hand for theater groups, plays, actors, models, bands, circus acts, etc. depending on who they handle. Maybe some talent agencies.
I hope that this helps.