Why use Bing Maps over Google? Bing's Map Apps provide some fairly intriguing reasons. Among them are map add-ons that show the best parking spots and cheapest gas along your route and around your destination.
You'll likely need to install Microsoft's Silverlight plug-in—and that might force-refresh all your browser tabs, by the way—but Bing's Map Apps are worth checking out for trip planning. They use geo-data from third-party sites like BestParking.com to find helpful stuff along your route, adding and adjusting as you zoom and move around the map. Tell us if you've found another Map App you dig, or a better gas/parking finder for trip planning, in the comments.