My boat's kept in a boathouse, so I don't have it tied to a dock for the whole season.
I use the hollow core rope like is used in ski ropes. I will take a 50' rope, cut it in 4 pieces and put an eye at each end of each rope. I loop one rope on each cleat on all 4 corners. Then, I keep another 4 ropes that can be looped together as needed. It's worked well for me over the years.
If I was going to permanently tie up my boat, I'd use more substantial ropes. When I pull tubers, I certainly use large ropes. There's nothing worse than having a break in a tuber's rope in a tight turn, and the riders having no control about where they go.
And I also carry a 1 1/2" 100' rope in case I have to tow another boat, or be towed. On our lake, we take care of each other.