You cannot use a stain and make all the different lumber match. That post and beam is ugly structural that shouldn't be exposed either. It needs drywalling, or to be miterclad in a wood box.

Have you had a floor finisher look at that flooring? It appears to me to be a prefinished product by the visible micro-bevels. You need to be certain the flooring can be sanded enough to get the finish out of those or the new finish will never work.

You're not showing us much.

That beam and column is pine. The railing I'm guessing is oak. Not sure about the flooring if it's' oak, but I agree with millworkman and this might be engineered prefinished flooring. If that is the case the surface is often aluminum oxide to resist scratching. If can be refinished, but it's difficult and expensive.

Yes, aluminum oxide wood floors can be refinished, but it is challenging due to the finish's extreme hardness. Refinishing options include recoating, which requires lightly sanding or screening the surface, or a full refinish which involves aggressive sanding to remove the finish completely before applying new polyurethane. Recoating

• What it is: This is the simplest method for floors that are in good condition. It involves sanding or screening the existing finish to provide a "tooth" for the new coat of polyurethane to adhere to.
• What to do: Lightly sand or use a screen to abrade the surface. A fine-grit screen (120- or 150-grit) is often a good starting point, but a more aggressive screen may be needed. You can then apply a new coat of polyurethane.
• Considerations: This is often insufficient for aluminum oxide floors because the finish is so hard that sanding or screening may not create enough of a bonding surface. For this reason, some professionals recommend a chemical recoating system instead.

Full refinishing

• What it is: This is a more intensive process that removes the entire aluminum oxide finish down to the bare wood.
• What to do: Start with an aggressive grit sandpaper, such as 36-grit Norton Blaze, to cut through the finish. Be prepared to use a lot of sandpaper and work in smaller sections. After the finish is removed, continue with progressively finer grits, and be sure to vacuum thoroughly between each pass to remove all dust and debris.
• Considerations: This is a difficult and time-consuming process that is best left to professionals with the right equipment.

Important notes

• Engineered wood: If your floor is engineered wood, check the thickness of the top layer (veneer). If the veneer is too thin, sanding could damage it, and it may be better to replace the floor.
• Dust collection: Sanding aluminum oxide floors can release a lot of dust. It's important to use a vacuum with a HEPA filter and a dustless system to collect the dust, as it can be harmful if inhaled.
• Follow manufacturer's instructions: Always follow the manufacturer's recommendations for your specific floor and finish. Some manufacturers offer specific instructions or products for refinishing their floors.

Hi originally it was supposed to be dry walled but then I liked the wood look so had the beam covered in pine
Panels. The floors are oak and were pre finished. Our floor guy is aware and said it can be done. Just wanted recommendations on a color stain. Thanks for your advice We are starting the work tomorrow I will keep you posted.