We spent one day swimming at Lido -- a Sunday in late August, and it was not crowded at all. We got off the Vaporetto at Lido and took a short walk along the main drag to the beach, turning left at the T when we couldn't go any further, and entering "Venezia Spiagge Spa" where we paid to rent "sun beds" (lounge chairs), an umbrella, and towels. We bought lunch there, at their stand, and it was delicious; much better than I would expect at a beachside stand in the US. Buses do stop right there. I think Lido has two bus lines.
Swimming was nice, along with access to very clean, tiled rest rooms. I believe there was a lifeguard. The facility controls a roped-off section of beach, stretching from the road, toward the water,almost to the high-tide line. The strip of beach between the rope and the actual water is public. We asked for one of the front-most umbrellas and were close enough to the water to enjoy it. Sitting in the roped-off "pay" part of the beach, we were only approached by one peddler. We saw more peddlers working the public part, but they did not seem to be ruining anybody's day. When people said no, the peddlers did not waste their time, but moved on.
The lounge chair attendant had little lockers for valuables, but we did not use it. We took our usual tag-team swimming approach. I would not walk away from valuables on any beach in the US, from NJ to Hawaii, so why would I expect to be able to do it there?
It's a little confusing about where and how to pay for, get, and return the lounge chairs, the towels, and the magnetic wristlet that gets you into the restrooms. But you will figure it out. You do need to get your deposits back, so I agree with a reviewer below, save all papers, tickets, receipts, etc. until you leave for good. Staff was friendly and helpful, despite my limited Italian.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.