Wiener Rundfahrten (Vienna Sightseeing Tours), Starhemberggasse 25 (tel. 01/7124-6830; www.viennasightseeingtours.com), offers the best tours, including a 1-day motor-coach excursion to Budapest costing 100€ ($130) per person. The historical city tour costs 34€ ($44) for adults and is free for children 12 and under. It's ideal for visitors who are pressed for time and yet want to be shown the major (and most frequently photographed) monuments of Vienna. Tours leave the Staatsoper daily at 9:45 and 10:30am and 2:45pm. The tour lasts 3 1/2 hours (U-Bahn: Karlsplatz).
"Vienna Woods -- Mayerling," another popular excursion, lasting about 4 hours, leaves from the Staatsoper and takes you to the towns of Perchtoldsdorf and Modling, and to the Abbey of Heiligenkreuz, a center of Christian culture since medieval times. The tour also takes you for a short walk through Baden, the spa that was once a favorite summer resort of the aristocracy. Tours cost 42€ ($55) for adults and 15€ ($20) for children ages 10 to 16.
A "Historical City Tour," which includes visits to Schönbrunn and Belvedere palaces, leaves the Staatsoper daily at 9:45 and 10:30am and 2:45pm. It lasts about 3 hours and costs 35€ ($46) for adults and 15€ ($20) for children ages 10 to 18.
A variation on the city tour includes an optional visit to the Spanish Riding School. This tour is offered Tuesday through Saturday, leaving from the Staatsoper building at 8:30am. Tickets are 59€ ($77) for adults, 30€ ($39) for children 13 and older, and free for children 3 to 12.
Information and booking for these tours can be obtained either through Vienna Sightseeing Tours or through its affiliate, Elite Tours, Operngasse 4 (tel. 01/5132225).