The south Pier would probably be the easiest to access. That is also the side they are having the SOTW tent and center of activities. Most of the boats that are participating will be moored there. From the SOTW tent you will be able to walk on the board walk that follows along the river all the way out to the pier. I would say it's very close to a one mile walk along the board walk but you can still be able to see pretty much everything as you go. Makes for some good exercise too!
Also, their is a camping area with a public beach with a ton of shoreline frontage to where you can park your car and watch the boats. As for myself, I usually park down by the SOTW tent somewhere as close as I can get and enjoy walking along the board walk. That way you can see many of the boats that are participating and be able to meet and talk with other boaters. There will be plenty of offshore performance hardware, equipment and activity so I doubt you'll be disappointed.