Hey @Anna Laud! What a fun project. And one I can identify with, as we are 95% done with a gut rehab of a 1915 home in NW Chicago which, like yours, came with a ton of original woodwork.
Unfortunately, we were not able to save the trim or casings because retrofitting them to all the new items & upgrades would have been cost prohibitive. However, we did salvage many of the original 7ft oak doors, floors, and the entire staircase. Now, that being said, our wood was absolutely beautiful. :) Your wood? I'm SO glad you posted pictures because I, three, was envisioning a totally different type of wood.
In case you needed more feedback (LOL), I'm 100% with @Seth Larson & @Aaron Schrader--PAINT THAT WOOD and modernize it the best you can! Even though our wood was gorgeous, I decided to paint our doors and staircase (combo of sanding/staining the treads and painting the balusters & handrail) because I felt leaving them the original darker color would have completely dated the house. As a compromise--because people in Chicago do love & appreciate some old world charm--we have gone with design fixtures and finishes that are modern/deco inspired. We're not totally done but below are some progress pictures.
I'd like to see your 'AFTER' shots when you complete this project, if you don't mind sharing. Good luck!
Jennie Berger, Property People