So my challenge is choice.
My boat has vinyl now. I do not know the brand, or the grade. The stuff in the pilothouse is much thicker, or to me harder than the stuff in the salon, which is very soft.
I do not have a problem with the vinyl feeling sticky in the heat, probably because it doesn't get all that hot here.
Everyone seems to love their Sunbrella upholstery fabric. Everybody seems to love their ultraleather. Everybody seems to love their Naugasoft. All for great reasons.
If vinyl will hold up to the abuse, I'm pretty sure it will be easier to clean spills off of it. It will also not absorb water from a wet dog laying on it.
Sunbrella on the other hand might be easier to sew, and is some pretty tough stuff. Part of the challenge is for me that I have zero upholstery fabrics anywhere in my life. My furniture at home is all leather, or bare wood. Even my truck seats are sheepskin so I have no history with fabric.
What I think I'll do is try the Naugasoft. I'll re-do the helm seat and the pilothouse seating. This will be a fairly simple first upholstery project. The Naugasoft is not a huge investment, and labor is free so if it does not work out I can just choose something different.
Thanks for everyone that provided their input!!!