I have a 29,500# 40' ketch @ Pier 39 in SF - known for having a lot of surge! I rock 1" three-strand docklines, three strand is really easy to splice, although you may need to retighten them a few days after docking as they have plenty of stretch under load. Two 100' lengths of 5/8" line should be plenty for most mooring situations, it wouldn't hurt to have one at 200' as a primary and a second at 100'. If you can get a great discount on a spool and have a garage to keep it in it is likely worth the money and the time saved on trips back to the chandlery. I like 30' lengths on my dock lines, allows plenty if you need to heave one in a tight jam, but on a vessel your size 20' would likely be enough. I tend to make up 30' lengths with a spliced eye at one end, reasoning that I can swap end for end or repurpose the remnant as a permanent fixed line I leave secured to my dock.
Many people here use motorcycle tires as snubbers, they seem to last much longer than the cheap rubber jammies available at West Marine you wrap a line around. Also much better than the bungee type snubbers. I've quit buying line at West Marine, I get much better prices and quality from a local chandlery that services commercial fishermen. Frequently remnants can be had for a fraction of the cost of line off the spool.
Sailing a '74 Challenger 40' Ketch rig out of San Francisco