First of all I still LOVE your chests! The mahogany color should be perfect (I used it for my MB vanity).
I really don't know if it will last on your set though. Do you actually use this set or is it a formal that you use a couple of times a year? I did my kitchen cabs and I've gotten a couple of chips (where the oak shows through) and I had to add more coats of polyurethane. I think the chairs mainly would start to show some wear and show the white.
What if you use a dark color primer first?
For the gel stain, I applied it with a sponge, waited a few minutes and then used a natural bristle brush to wipe some off/smooth it out.(sometimes I used a regular brush and it worked out fine). I called it "dry brush" because I didn't dip the brush in the stain. Every once in a while I would use a rag to clean some of the excess stain off the brush.
I did two coats. You have to wait at least a day to apply the second coat. It will feel sticky if not dry.
Then I did four coats of polyurethane.
I used walnut on my cabs and mahogany on vanity.

I also used the gel stain as a glaze on a white cabinet in my guest bath. I had painted it white then I used the stain to darken the corners a little bit. I had a whole can of this and didn't feel like buying the glaze. I just wanted to mention that it really stuck to the paint. I brushed it on and then ragged it off and it looked great.
So my point was that it will really stick to paint.
good luck
Mariana

Rather than try to change the entire look of your white-washed pieces, I would do as mkraff53 did and just antique them with the get stain. I would rather see a contrast between your table and chairs and the mahogany pieces. The problem is the table and chairs appear to be a pinkish-gray and when you put the gel stain on top of that your are going to have to put many coats on it to get the color you want, losing the grain of the wood. By antiquing those pieces, you can get a complimentary color, keeping some contrast. I would caution against mohogany though because some of the mahogany gel stains are very purple, making your set even more pinkish. I would use a cherry or a dark oak stain first to reduce the pinkish gray color in your set. Also make sure that the gel stain you use is liguid, not the really thick one, because it doesn't do well over painted pieces; it drys too fast. Test on the least visable are first!
Diane

Mlraff, no we use our dining room every evening for dinner and weekends for breakfast. Hmmmm, this has me concerned!

Powermuffin, I'm not so sure I'd like the table and chairs white, but antiqued.

Does anyone know if I'd see any (faux) graining just from the Gel Stain over a dark primer instead?

Lynn if you painted your chairs first, or did the kind of rough and dirty painting I did on the tv cab, you could get a linear faux grain look with the gel stain. But it would be more difficult to fake it in the carved areas. P/muffin is right about the mahogany color - it often goes wrong but there are lots of choices and you can combine colors. I happen to like the thick stuff in the can more than the liquid - personal preference. You'll never match your new pieces, and I wouldn't try - I probably wouldn't even want to be close because the feel of the pieces is totally different. I'd go for complementary contrast. I can't remember your layout - can you see the DR from the new kitchen?

You won't see any "faux" grain unless you have a different color underneath. You will however see the real grain.
Since my cabs were oak, as I was "brushing" the stain, depending on how many strokes I did, it looked like wood grain. If I added more stain, then it would all get dark.
You can't really see in the picture other than the oak wood grain.
From what I know with my cabs, I would be hesitant on doing it on my table and chairs. What if you paint them a dark red and then do the gel stain on top. Someone had done their cabs like that and they looked great. Plus if it chips, you'll see red and not white. Whatever you do you will have to give them many, many coats of polyurethane.

Don't forget that the set still matches the architecture of your house. Maybe you should leave the chests as two items that stand out and not make the whole room blend together. A dr set that matches the chests will never match the molding or the floor in your room.
You have a very nice eclectic space. If the set is "pinkish" then stain it to get rid of that (maybe closer to the molding around the doors).

You could use the dark gel stain on only the carved areas. Make sure it gets into the crevices and then wipe if off.
It would add some darkness to it and tie it in with the rest of the furniture.

We dark gel stained our pine kitchen table and, yup, we get little dinks and chips periodically. I don't recommend doing it to a heavily used surface. Here is another thought. Why not leave the table and chairs alone and live with the contrast? Maybe change out the chandelier to match the new wood pieces. Maybe change the uphoulstery on the chairs to a deeper color, closer to the new wood pieces. The contrast could be fun, just tie them together more by editing out stuff.

Lynn,I don't remember if you've seen pictures of our master walk-in closet with mahogany gel stain by Minwax. We used MDF. I applied the gel stain with a good quality brush which left a sort of grain. You know the color of MDF. Well this is what it looks like after staining.

I'm not sure how it would look on your white washed dinning set without painting it a darker color first, but couldn't you try it on the underside of a chair or table to see how it looks first? Just a thought.

You can faux grain it, but as previously stated, you need to paint it a wood color, like caramel, first. The reason I like the thiner gel stain for this project is because it is on paint, rather than stain. I have found the thick stuff to work best on stained pieces. I suggested the antique look because you indicated that you wanted to keep the grain. This set is never going to look like it matches the two cabinets and I don't know why you want them too. It would be a lot of dark stuff in that room and then none of the pieces stand out. If this were my room and I did not like the color of the dining room set, I would paint it slate blue or red or gold, something that coordinates with the rest of the house but lets it stand out on its own to be a focal point.

I don't think gel stain will work for you in this application.

If it were me, I would do a faux finish. Try this first on a sealed board, of course.

Paint the first coat a deep, reddish brown -- approximately the lightest color of the two other pieces you want to match -- the "highlight" color of the two pieces.

After that coat dries, apply a coat of very dark reddish brown paint -- the "shadow" color of the two pieces. Working quickly and in small patches, rub this coat off roughly.

See if you like the result.

To approximate real wood finish, you should work with high-gloss paint; and after you're done, varnish the whole thing to give it some depth.

Thanks for all your advice. I'm so glad that I didn't just rush in and start this. From the sounds of it, I WOULD HAVE ruined them . . . :^0 . . . OMGosh!
I need to run all this by DH. He's been encouraging me to call up and order a set I like that I saw in Phoenix Home & Garden magazine spread. I can't imagine ordering anything that big and expensive sight unseen, though.
Hmmmmmm, there may be a weekend trip to Scottsdale in the offing ;^)
In the mean time, I need to decide whether I want to paint the set a brown first and them give the Gel Stain a go or just leave it as is until I get a new set. BTW, I haven't looked into having it professionally stripped and redone. I probably should.
I can't imagine a red or blue table in our dining room, though. I'll have to think about that one.

We have been changing all of our golden oak to mahogany using the Gel Stain. We plan on doing our table soon. I would definitly sand the table to get any finish off. Sand it down to bare wood then you can apply the gel stain. I found that sponge brushes worked best. After you get the desired color let dry completely and seal it with a varnish that is suitable for dining tables.

Sand it all down? Yikes! Have you seen the amount of tiny carving on these pieces? Does anyone know if Liquid Sandpaper would get all that off? Any other ideas on how to sand each tiny crevice? I'm not opposed to sanding the flat areas, but it would take weeks to sand that small stuff and we eat at this table six nights a week, not to mention breakfasts. Any ideas would be greatly appreciated!