Spent nearly all of September in Central Europe -- week in Austria, few days in Czech Republic and a Rick Steves Central Europe tour. (Tour guide, Jana, was wonderful). Salzburg lodging was at Hotel Blobergerhof, about 5 km from the city. In RS guidebook. Bus stops within two blocks of lodging. Ride to city about 15 minutes. Easy. Food and room were excellent. About 100 Euros a night with breakfast. www.blobergerhof.at
One day stop in Hallstatt - easy trains from Salzburg -- well worth it. Might suggest two days. Beautiful lake village. Rained heavy on our stay. Pension Gruener Anger good lodging about 7-8 blocks from town center. About 100 Euros a night with breakfast. In RS book. www.angere.hallstatt.net
Train to Vienna for five nights. Lodging at Kolping Wien Zentral at about 100 Euros a night - with breakfast. Not fancy, but clean and staff friendly and helpful with suggestions on neighborhood cafes. Great location -- about 6 blocks from city center.
Those are absolutely some of my favorite cities. There's so much to see throughout Austria that a group tour does help.