Another option that might work depending on where you live is http://ridethecity.com/

I find Google maps to be fairly accurate for sub-10km (6 mile) rides when traffic lights and conditions are likely to have a more significant impact. For your 30 mile ride, I assume (hope!) that a lot of it is open roads, where you can probably cruise fairly easily at 12-15 mph. If it was 30 miles of stop-and-go city riding, I would look into multi-modal commuting.