Fly into Munich, see that city. Rent a car, hit Liechtenstein (just to say you did it), then Milan. Then head to Venice. It’s an easy drive, beautiful country, and a LOT cheaper than flying into/out from Venice! And if you have time, Zagreb and Vienna on the loop back to Munich.
It’s about 20 hours of road time, total. Spread out over 7-8 days, that’s nothing. Cut that time in half by dropping the trip back from Venice to Munich via Zagreb and Vienna.
It’s not the airfare that kills you. It’s the lodging. Ridiculous!