Oh my gosh- if you were in Tampa no question! Salvation Army or Missing Piece. I have to stay away sometimes they have so many really nice solid tables, and unique pieces that you don't see everywhere.

Most higher quality furniture gets donated.

Is there a company called Habitat for Humanity? Our HFH has stores called Restores, where there is a lot of donated furniture. Also, look for "mid century modern" in your Craigslist search. Those tend to be smaller.

ebay, you can refine searches to free shipping or a certain mile distance to make pick up easy.

Do you have furniture consignment stores in your area? Also, these days, antique stores are not necessarily antiques only(too expensive)so vendors are selling furniture from every era, but usually more traditional in style. Estate sales in your area can also be found on line, as are auctions. These could possibly be your best sources for quality used furniture.