Re: What type of sealer to use
I guess one big factor that I would keep in mind is how slippery it will be when wet (and it will get wet). A hard finish will be VERY slick unless some non-skid grit is sprinkled into the mix, which is an option. Although doing this with a high gloss finish doesn't look the best IMO. I've always recommended an oil for this kind of area. There is some up keep to preserve the appearance, but it's very easy. Probably about 10 minutes of work once a month if it sits in the sun everyday. The other advantage of oil is that it does not lose it's traction when wet. Something to think about.
Good luck!
~BWT