Wood facia, if it is mostly solid, can be covered with aluminum facia if the rafter ends are solid. I would use aluminum facia, because although it can be dented, it won't shatter. Vinyl is nice too. It might be a toss-up. It sounds like a second floor job, but pump jacks or ladder jacks are an alternative to scaffolding.

I've installed both vinyl and aluminum and I also think the aluminum would be a better choice for facia. The vinyl seems to have a tendency to expand and contract more, forcing the nails to start creeping out. That means going back up and renailing them sooner than with aluminum. The nails creep with aluminum also, but don't come out as far.

We replaced our facia, gutter and soffits in our last home and we used aluminum. Our soffit and facia was not in bad shape but had been painted over stain and it was peeling and the gutters were in terrible condition. I could not believe the difference in the house with the new soffit and facia.

You can use either vinyl or aluminum or a combination of the two but the first thing you need to decide is whether the existing fascia is going to stay or be replaced. If it is not sound wood, you'll have to remove it and replace it with 2x6 lumber. Remove the soffit as well and nail up a channel (positioned such that the soffit material will be level) on the wall to support the vented soffit material. Cut the soffit material to the correct lengths and insert one side in the channel and nail the other side to the bottom of the 2x6.

The fascia pieces then get tucked under drip edge coming off the roof and can be nailed from the bottom and the face (if necessary).

It is important to have the sound fascia material so you can firmly attach your gutters.

On my last project, I used vinyl soffit because it is easier to cut without getting it all bent out of shape. However I used aluminum fascia (pre-painted white) because it is light and easy to work with and not that difficult to cut. You can't really tell by looking at it that I used different materials.

You might also want to replace the gutters while you're at it to give a nice clean/new look.