The Canal Walk - Upper Basin
I think the Upper Basin is the easiest location to find and park on the Canal. It's the very top of the canal There is metered Parking on West 11th Street and the surrounding areas. You have great views of the city and the canal from the street level and easy access down to the canal. It's handicapped friendly! This is a fantastic place for pictures! There is a bridge you can duck under if it rains!
A few things to think about:
Timing. Canal 337 is a formal wedding venue, they may limit access around their area or have the street level area with the view of the canal reserved for private parties. You can also reserve that area of the canal for your wedding too - you do that through the city. They have bouncers limiting access to their area - but you can still use the canal - you might not want to elope while other people are getting married!
The fountain walls are really cool! There are places to sit right around there and it seems like the perfect spot. BUT - it's also REALLY LOUD. Your guests probably wont hear anything we say. You may want to get married at a quieter place and then take pictures against the wall.