I think I'd keep all the floors uniform. IF you go with lighter upstairs, then I'd suggest you go with lighter downstairs, too. Really dark floors are also common in modern homes. What about a rich, medium stain?

I know what you mean about dark floors! One home we lived in had them and although they were gorgeous they were a pain to keep clean!

Anyway, I think I'd go with a medium stain for upstairs........either the walnut, a medium oak, hickory, etc. If you're trying to get away from contemporary, then stay away from the really light flooring, but I don't think the upstairs needs to be as dark as the downstairs. If you stay with a medium stain it will all blend well and not be a jarring change.
I don't think using two different woods on the same level is a good idea...........ie: hallway leading into bedroom.

DIL just had her red oak flooring refinished with a light walnut stain ...........looks great without being too dark or too light.

Thanks annz! We looked at the medium stains and really didn't find anything that grabbed us...we liked the grain in the natural and the 'wow' of the dark, but not so much anything in between. I found most to be too orangey, I don't know if that's just the way that maple stains?

I forgot to mention before, but one of the reasons we are going to go with maple is that we really would like to buy wood flooring that is FSC-certified (sustainably harvested) and preferably from a local source and we have been able to find reasonably-priced maple floors that are both. The other option would be reclaimed wood (dragged out of the river and then milled). It's GORGEOUS but I'm thinking it's likely too rustic and a little pricey.

What if we had the dark maple throughout the upstairs - could we switch to walnut in the master?

Here is a link that might be useful: Reclaimed wood flooring company

Is the area the maple will be in connected to the master?

You may find more advice on the Flooring forum, but I did a quick search on Maple flooring and most sites said this:
***Due to the extremely tight cellular structure and the variable grain patterns inherent in northern hard maple, the MFMA does not recommend bleaching or staining. Northern hard maple does not stain and/or bleach uniformly and attempts to bleach or stain may result in a mottled, blotchy appearance.***

gwen
A few thoughts
If you plan on having children - one thing to consider w/HW instead of carpeting upstairs is noise - carpet does deaden some of the noise and also provides warmth on those chilly mornings when the tootsies hit the floor-

sheet rocked homes vs. plaster are noiser & older homes in general are chillier

I have HW upstairs & toyed w/the idea of letting at least some of them show - instead I bought nice new wool blend carpet that is heavenly to walk on - keeps noise down, and it's an older drafty home so does help in colder months
the hallway & stairs (dutch colonial) are HW - I have a oriental in the hallway.

I hear you on the darker wood showing everything -
If you are having site installed hw - they will need to sand & stain once installed - you could have them sand the downstairs and find a medium stain and have all the floors matching.

Good luck

I don't think there is anything wrong with having dark wood and light wood in the same house, especially if they are on separate floors. We have dark walnut floors in our LR and right next to it, we have light oak in our DR. The floors are separated by a walnut saddle and while it does take getting used to its not bad at all.
We did this b/c our LR was newly renovated and we were supposed to go with oak floors but I changed my mind last minute.

I think you should do what you want. If light maple is what you want in your MBR, then go for it. It's your house and if you do end up going with dark b/c someone else talked you into it, just remember that "someone else" won't be the one cleaning and mantaing the floors. LOL! Good luck.

annz - Hmm, I don't know about maple taking stain...the dark floor we have downstairs is maple and the stain is nice and uniform...???

jejvtr - Yes, I know about the noise (grew up in a house with wood upstairs, later carpeted over, now my parents are pulling up the carpets - it all cycles around, doesn't it?). I think we'll end up with rugs, which is fine with me. DH has allergies too, and we have a cat, so between the two, the hardwood is probably healthier. At least rugs can be cleaned regularly (and, of course, changed when the decor requires, lol!)

I have a friend who just did a bedroom in bamboo flooring and it's beautiful. She had a choice between light and dark and chose the light. The "grain" is very fine...looks great.

Whatever you do, I'd strongly suggest NOT sanding what you have and staining that light/natural. Even though you sand through 100% of the existing stain, it never really takes the light stain that well, even with conditioner. Also, sometime's you'll notice the darker in the cracks, where it bled down but didn't get sanded. Floor guys may tell you otherwise, but really caution against this. We had dark floors, added light upstairs and had the existing stuff sanded and stained light and it just looks washed out to me. Thats with a few coats of stain. Wife has never let me live that one down.

The cost of re-do'ing it is one thing. Much worse is having to basically move out of the house again.

People cautioned us about going with wood floors upstairs with kids due to noise. That really hasn't been a problem for us and we like the wood. Just don't kid yourself that doing wood is going to be 30% more than good carpet. After the floors are done, then you start the rug shopping! Which isn't bad, but isn't cheap.

Good Luck!

I would keep the floors species and color uniform on one floor, my opinion.
We have dark floors but in a very low sheen and they are really easy to take care of. They look very rich. However, I don't know how maple would look in a low sheen as I haven't seen it. The lower the sheen the easier they are to maintain.

backsweat - That's good food for thought. I hadn't considered NOT being able to strip the dark stain downstairs. The rug cost is a good point too, especially since I already have my eye on a few.... Think I said it somewhere above, but the natural maple is about $3/sq-ft. cheaper than the dark-stained stuff, which is definitely part of the appeal (leaving extra $$ for rugs, of course!)

Chinchette - our existing maple floors are a low sheen, the only high-maintenance part of them is that when the light hits them, you see every speck of dust/cat hair, etc. I'm not an obsessive housekeeper, which probably doesn't help... The natural maple we're looking at is a low-sheen, environmentally friendly finish and it's very nice (and hides more dust!)

Methinks it might be time to stop into the flooring place and bring home some samples...