I highly recommend to visit both during the day AND at night (if you're not staying around the island itself). Why? The atmosphere is different. If I have to be honest, I would much rather go at night than the crowded, hot, sticky day. I also didn't get to go on the gondola because my parents were adamant about it, because it's 'too touristy' and not a big deal. I'm making it a mission to go on the gondola next time..
During the night, we saw some bands play at the restaurants around the city square. May I say, it was some of the finest jazz music I've ever heard. I would've loved to just dine outside and listen to them for the night.
Ristorante Antico Picnolo. We had some pasta, fish and tiramisu! The tiramisu was some serious authentic tiramisu, I wish they could've given us two slices!
So, I really do recommend to explore Venice by night!
So, Venice is on my 'favourite places' list from my trip. Although, I visited some other beautiful cities like Rome, Venice is something different. I love the atmosphere there, and you can't beat the scenery you get there.