I've given up on Venice at anytime, but winter. It is way too crowded between March and November to enjoy what is a most magnificent city.
That said if you fly into Venice the northest corner of Italy(Veneto, Friuli) is full of gems still largely off the beaten track. Trieste is a great and underrated city. The Gorizia Hills/Goriska Brda straddling the border of Italy and Slovenia is a beautiful wine country with excellent restaurants and the relics of some of the bloodiest battles of WWI nearby.
Should you want to go straight to Bled from Venice, taking the train is a much nicer experience than a cramped shuttle bus. Here is the nitty-gritty: https://www.seat61.com/trains-and-routes/venice-and-trieste-to-lake-bled-by-train.htm
Other than northeast Italy, the other logical pre-tour stop would be Austria, with good train connections via scenic routes to Lake Blad and Ljubljana either from Salzburg(in this case flying into Munich makes most sense) or from Vienna(Graz is a great stop between Vienna and Ljubljana).