%% IF you want to get fancy; could use a brush to trim board next to handrails LOLPlenty of people leave those small knot holes empty.
Ken has a long history of liking to fill cracks and holes. Oh wait, you were talking about decks. Nevermind. My bad.
It looks like you have an " upper " deck to redo as do I. Is your deck over a part of the house? Ours is over the sun room and so there are some things to consider. First off my deck is falling apart. a black bear climbed up the tree and ripped apart the railing- huge gaping hole now by the bird feeder you could walk right off-- There is a paper you get from HD that you lay down first waterproofing<-- Important if you have tough winters as we do in Ct. You will need a dumpster and those are hard to get. We had to wait a week. Also the trees have to fill in to avoid preying eyes. Next all these wood pillars yours are rather simple looking, ours have a lot of detail-- who is going to cut those? You need a guy. The floor laying is rather simple you have beams that run across underneath and a small amount of space to put the nail but once you get one in the rest can cluster. It is the side railings though and the security and strength of the whole affair and the need to be up on a ladder -- it is for those reasons I suggest you hire someone. If you are just doing the floor with a stain you can probably wing it but I am replacing w/ all new wood because of severe warping. Enough stubbed toes! Work begins this next week!
When I was young I had a time share in Fire Island with an Upper Deck. We used to sit out at night flying on ecstasy talking and laughing until the next morning we called ourselves " The Upper Deck Heroes " I miss those days.