Hey Bill, what decision did you arrive at for these doors? Would love to see some pictures!

In my house, our stairs are carpeted and the upstairs/downstairs levels are floating floorboards. The stairs worked out too expensive to do so we changed carpet colour to compliment the colour of the timber. It looks fine :) I think they're separate levels and you won't see them together so should look good either way!

Can you post a close up picture of the wood showing the grain, please?

I agree, it looks like Blackbutt tongue and groove timber, like I had in a house I once owned. Blackbutt is one of the hardest wearing timbers. The photo shows how it looked when the house was on the market for sale. It had not been re-sanded or re-polished since it was built 16 years prior. It still looked as good as new. The timber looks lighter than in your photo as all the lights were on when my photo was taken. If your house was built earlier, it could be one of the gum species, eg spotted gum.