I did the 109 mile ride last year. The century route is probably not the best for beginners -- there's a mass start, and a lot of paceline riding for the first 20 or so miles. The shorter options are probably better if you've never done an organized ride, much less a "race" before. The route is pretty flat, many/most streets have traffic control, and there are actually people cheering all along the course -- especially at the finish.

Go for it!