Two things you need to know about gondola rides in Venice: 1 - They're worth it. 2 - The price is agreed beforehand, and is standard.
Knowing those two things, you can happily hop aboard this traditional Venetian mode of transport and relax, because, touristy as it is, it's not a rip-off, and it's a must-have experience.
You can pick up a gondola almost anywhere in Venice, and you can see whatever sights you want from one... my own recommendation is to head away from the Grand Canal to the quiet backwater canals where you can really imagine yourself centuries back in time. We engaged our gondolier at the station near Rialto Mercato and asked him to take us across to Cannaregio, a more residential area that still boasts some extraordinary palazzi and churches. We barely met another boat, apart from the odd Venetian getting himself home on his motor launch, and unexpected delights loomed upon us silently and suddenly, like Marco Polo's house, or the Chiesa dei Miracoli. All in all, much better than joining the heavy gondola traffic in San Marco.