I haven't done this, so apologies if it seems non-responsive. I wouldn't do it because I'd be interested in pulling together the whole house (or at least the common areas) into a cohesive decor scheme to give an overall feel. It's hard enough when the floors are the same!

One thing that I've struggled with (and maybe you are too), is seeing an image of something very, very appealing, and then scheming about how to carry it off in my own house. But I'm learning(an ongoing process) to work with what exists in my space, because I don't have an unlimited budget and need to spend frugally and wisely. Both dark floors and light floors can look incredible, and perhaps there is a way to execute it, but I haven't seen any of doing half-n-half in the places I go for inspiration (blogs, designer websites, etc.). (which obviously doesn't mean you can't do it, just that it's not commonly done).

I think it's wiser to either match what you have, or replace/refinish all of what you see to make it cohesive. Maybe post some pictures of what you have, and others can see what you're dealing with and trying to achieve.

Yes people have done this. Yes there are examples of it. Yes there has been and will continue to be push-back from other people NOT TO DO IT! And yes it affects future resale (assuming resale is in the next 15 years or so).

Here is what you will NEED TO KNOW so that you can make the RIGHT DECISION for you and your family and your house (the entity that you bought for $$$$$$).

1. Find out the SPECIES of "oak" that already exists

2. Find out the CUT (quarter sawn, rift sawn, plain sawn) and the WIDTH of the plank

3. Is this SOLID hardwood (sight finished) or is this engineered/factory finished

4. How OLD is the existing hardwood - does it need refinishing

OK...those are ALL QUESTIONS you MUST ANSWER before going any further. IF....big if...these are SOLID SITE FINISHED oak floors, you can order/purchase more of the same species/cut/width of plank. The SPECIES MATCH is SUPER DUPER IMPORTANT (that's why I'm using caps)! The cut and the width are also important.

You can then weave or lace in the new oak to the existing. Then the flooring professional can then sand and refinish EVERYTHING AT THE SAME TIME! Done.

It gets complicated when this is not site finished hardwood. And it gets complicated when the homeowner does NOT want to refinish everything at the same time (under the guise of saving money....that always costs more later on down the road).

So...first things first: Call in a WELL EDUCATED and well respected hardwood flooring professional (someone who works for a Ma & Pa hardwood flooring store that has 25+ years of experience) to come in and have a look.

Have your wood TESTED for species match (assuming this is solid/site finished product) because tooo many times we have seen red oak floors "matched" to white oak by mistake and then BAM! Nasty shock. It costs about $100 to have your wood tested. Takes about 1-2 weeks to get the results back.

If you insist on having a new wood put in and stained differently, then PLEASE get a species match. That gives you and the future homeowner to have the SAME FLOOR throughout the space. It is the best you can do if you do not want to spend the time/money on refinishing the existing hardwood. You will kick yourself if you don't.