I would definitely suggest taller and wider night stands for that bed.

If you'd like to keep the nightstands, I would consider putting one of them between the two chairs as an end table and one of them elsewhere in the home. Since the bed area is typically a focal point in the bedroom, if the nightstands are too small in scale compared to the bed, that area will not look optimal from a design perspective. Different nightstands would also help move towards your goal of having mixed vs. matched "grandmother" pieces. Ultimately the choice is yours though so you should do what makes you happy.

I also prefer unmatching (for all) furniture. I like the idea of taupe walls & very light monochromatic colors in a bedroom. You could choose an unmatching dresser in a white or antiqued in a light color. Since you have some time, choose carefully as you will probably be living with your choices a long time.

Amagansett Beach Retreat · More Info

Be sure to select your art and some plants & since you will have accent chairs, add a small bookcase & books you like to reread.

While I think the nightstands do seem a little undersized, I think it's more that the mattress is so huge, it's hiding most of the headboard. If you can, I would swap out the box springs for low profile ones, it'll make the bed feel more balanced. You have some great pieces of furniture, and I think that dress would really go well. If you're trying to make it a little less granny's attic though I would go with a more bold wall color than taupe, and for the duvet, perhaps something a little more classic but modern like this: http://www.wayfair.com/The-Pillow-Collection-Sophia-Bedding-Collection-KX2970-KX2970.html

For the walls I'd go with a mid-tone muted blue or green, or a warm honey gold. The chairs have a nice shape, but I think they're going to read way too traditional if you want to modernize the look of the room. I think a basic stripe on them would look better.

Other option would be to just embrace the traditional look of the furnishings, and you could do a bedding more like this:

http://www.wayfair.com/Eastern-Accents-Aston-Hand-Tacked-Bedding-Collection-EAN4900-EAN4900.html

The nightstands, though charming, are far too small to compete with your bed. Most four posters have chests that align with the height of the mattress. That way the lamps are at the appropriate light. Maybe the nightstands can be reassigned to a guest room.

If you cannot match the bed in finish, which is rather unlikely, i recommend you consider two painted antiqued chests on either side of the bed and also a painted dresser with art mount above. Mixing wood finishes and painted finishes should work well together.

Wait until you move into your new place before getting rid of anything.

If you like the piece, don't get rid of it or you will likely regret it.

Instead, repurpose it but only if YOU don't think it belongs with your other furniture. All your furniture does not need match as if it were a furniture store showroom; in fact, it will likely feel more like home if it doesn't. What matters is what you like.

Will your new home have an entry in which that mirrored dresser would fit?

Is it an antique? If you don't know, find out.