We just returned from 6 wonderful days in Venice. Yes, in August.

The key for us:

1) A good travel planner to help organize the itinerary
2) We rented our own apartment 'embedded' in the neighborhood (Dorsoduro)
3) For the popular destinations, we had our planner arrange a guide. This way we did not have to wait in line at all.

It was hot, and muggy at times - evenings would cool some, but still short sleeved weather. We loved it.

We generally avoided the most crowded places (Rialto, San Marco, Accademia) during the day unless we had a tour / destination on the schedule.

No high water, no smell from the canals. (What time of year is worst for odors?) There are mosquitoes.

It did rain - One night was a torrential downpour with strong winds. Fortunately it had mostly blown through by morning. We bought umbrellas and carried them, but did not really use them much.

We spent an incredible day at Lido Beach.

Some stores, and even restaurants and wine bars, close down for some or all of August.

Cicchetti touring from Bacaro to Bacaro in the evening before dinner (from 6:00 - 8:00 or so) was incredibly fun. Then dinner at 8:00 or 9:00, again, still warm enough to sit outside in short sleeves.

There were cruise ships and crowds, of course. While annoying at times, we did not let this deter our enjoyment of this beautiful city!

Highly recommended: Cooking school with Enrica Rocca or one of her associates (highly ranked, easy to find on TA). Truly ended up being one of the highlights of our trip! (Thanks Marloes!)