Flush Wood Registers are the way to go. Make sure to get the vents with the damper on the bottom so you have the ability to open and close the vents.

Here is a link that might be useful: Precision Flooring

Thanks kitchenkrazed09 -- this is just one of a million decorator questions I don't feel equipped to answer. Aaaagh!

Donnie Gupton -- thanks for your opinion too -- but if you are affiliated w/ precision flooring, we already have a flooring guy who won't warranty the work unless he supplies it.

I would second the wood registers. That is what I put in our Great Room when we remodeled. The wood registers disappear into the floor as they have the same finish and are flush. I do not know if your metal registers would be flush? But we had the metal registers that were attached to the baseboard and the floor, so were pretty ugly.
Your floor guy should be able to supply wood floor registers to match.

We get the most compliments on our flush wood vents. People can not get over how much better they look than the metal. We install them as a matter of coarse with every floor we sell.
The only time we were asked not to use them was when antique cast vents had been purchased by the homeowner.

When dh and I were building our house he wanted the wood vents and I didn't care! But, now that we have them I really do like them. I don't think they look "country" at all; just like 'ricew0'said, they disappear right into the floor!

I should have mentioned what I had in mind were the pretty metal registers that have more detailing. Some are scrolled or have a filigree design. If you search "metal floor register" under Google Images, you can see some examples. What about something like that? (Of course, I'm not sure how much they cost.)

I replaced my registers when we had walnut floors installed in our old house. I bought elegant bronze ones with scroll work. Our house was a European tudor style. Everybody ooowed and awwwed over the floors and the registers. A lot of friends had never seen registers like those before and kept asking where I got them because they wanted to change out theirs

Hi everyone - thanks for your thoughts! I posted on the decorating forum where I got confirmation that flush mount wood registers are not 'country'. But one consideration may be the amount of air flow...

Ours are the plain grayish/brownish painted metal ones that sit on top of the flooring or carpeting. I don't even notice them anymore - - but the flush wood ones will be so much less obvious. Thanks again!!!

The newer high flow wood vents now equal the flow of metal ones.

Woodfloorpro -- which ones are the newer high flow wood vents? Where can we find them?

We are just finishing a large reno, and our design/build firm would not install flush mount wood registers as they have had trouble with these products in the past. Apparently they break easily if you step on them the wrong way, and are then difficult to replace.

I have matching Brazilian Cherry Wood floors vents that go on top and I am very happy with the look.