Lake Garda offers an infinity of attractions, so you can always come back and see new things.

Gardaland - fantastic adventure park between Lazise and Peschiera del Garda

Sealife - magic acquarium just in front of Gardaland
Movieland - adventure park based on great movies next to Lazise
Caneva World - great waterpark just next to Movieland
Medieval times -  Medieval dinner with knights and horses, also by the Movieland
Rio Valli - very nice water park in Cavaion Veronese

Cavour - another great water park in Valeggio sul Mincio
Jungle adventure park - fantastic place in a little forest in San Zeno di Montagna

Parco Natura Viva - great safari park and Zoo in Pastrengo
Terme di Colà - great thermal garden with hot ground water, in Colà di Lazise

Acquardens - beatutiful therlam park in Pescantina
Waterfalls of Molina - beautiful park in Molina (take comfortable shoes with you)

Mountainbike - There are lots of places to go! 

Trip on the ship 

Trip on the ferry by car -> Connections: Maderno - Torri del Benaco , or Limone - Malcesine.
Malcesine and Monte Baldo - beautiful town in the north of the lake, with the lift to the mountains
Verona - Arena in Piazza Bra, Via Mazzini, Piazza Erbe, House of Giulietta, The Old Castel, Teatro Romano...

Arena and opera - you should visit the arena and see at least one opera, unforgettable experience.
Venezia, Milano or Trento by train 
Shopping - Grande Mela, Adigeo, Il Leone, Auchan

Outlets - Mantova, Salewa, Olip shoes...