We got married in Lake Garda last August - couldn't recommend the place highly enough!!!! I would suggest flying into Bergamo, a lot of people at our wedding did this and drove to lake garda, no majoy complaints about this from the guests (although I would recommend using/borrowing a sat nav) if you're driving yourself, they said this made the journey way less stressful. We went to the opera too in Verona, fantastic experience but make sure you're prepared for all weathers, make sure you bring some kind of wind breaker because as the performance goes on and it gets late, the place is freezing it's so high up in the arena. great experience if you're prepared, we weren't and were a bit miserable cos we were so cold. We were also a bit unlucky because it started to last rain midway through the performance so it was abandoned, I had heard before we went that this could happend and I kind of thought people exagerated but it's true. You can't plan the weather so my advice is to book and go and hope for the best because it is worth it.
My brother in law spent some time in Rome before making the treck to LGarda for our wedding and they took the train, they did find it a very long journey because they had to get a few connections (no direct route from Rome to Riva, north of the lake) - just to warn you it was a long journey but they did say it was worth it because they loved both places.
If someone else has suggested Torbole for the windsufing you prob should look at that but I'd also recommend Riva on the north beause this is one of the main resorts and loads to do from here. Very reasonable to eat out and local wine is €2 a glass and way toooo nice.....
Would love to be going back this year so where-ever you end up enjoy it because it is one of the nicest picturesque places we've every been to!!!!