I’m trying to make my own window sills in our new house. We have windows rather deep so depth is around 9in and wide - 42/60in. I’m looking at read oak vs douglas fir. Red oak is mainly available in sub 8in cuts. The only one I found in 9in is 3/4 thick. Would that be sufficient to support plant pots or potentially human sitting on them? However Fir I can get in various sizes so I was looking at 1in thick.

Which one would be more practical? Oak at 3/4 or Fir at 1in?

My reading was that fir is sufficiently softer so plant pots may leave imprints etc. or am I wrong there?