change hardwood floor color without full stand?

[mound]

I'll be moving into a new house this summer and the house will be empty for a several week window. 
The house has oak hardwoods throughout including oak staircase. All just with a clear finish (no wax) - standard honey color oak. Part of the house is older thin strip, part of it is a newer factory finished (a bit darker) and the master bedroom will have the carpet removed, and an unfinished oak installed. 

The goal then would to "refinish" the whole house worth of floors in a consistent / darker color. This would really be the only possible time to do such a thing. 

Does this require sanding everything down to bare wood (which is what I've been assuming) or is it possible (gel stain of some kind?) to put a consistent color on all the floors and recoat with poly, without sanding them all first?

I do plan to hire this work out but want to get a feel for options from folks here who may know the answer.

[JosephP]

With different vintages you probably also have different finishes.  Those will affect how the wood takes stain. If you really want a match throughout I don't think there's any realistic way to do that except getting back down to bare wood.... And even then the different kinds or ages of wood may take the color a little differently. The darker you go the easier it will probably be to match.

Frankly I'd be thinking pretty hard about how bad everything needs to match! Are all of the board widths the same? If not maybe you could leave the new stuff alone and just refinish the old???

[mound]

With different vintages you probably also have different finishes.  Those will affect how the wood takes stain. If you really want a match throughout I don't think there's any realistic way to do that except getting back down to bare wood.... And even then the different kinds or ages of wood may take the color a little differently. The darker you go the easier it will probably be to match.

Frankly I'd be thinking pretty hard about how bad everything needs to match! Are all of the board widths the same? If not maybe you could leave the new stuff alone and just refinish the old???

Yah you're probably right. Matching board widths isn't as important as having the same color everywhere I think.