On our long dining room table, I added a natural looking runner (which is actually a role of drawer liner from the Container Store).
The whole look is very symmetrical and simple- which I like...for now!
I used my homemade terrarium for a centerpiece on our kitchen table. Then I added four woven place mats that I picked up from Home Goods for $5 awhile ago.
The last thing I did was fold some rectangular place mats (from Tarjay I believe) and layer them on top of the woven ones, to add a little more depth and interest to the table.
Both of these looks were simple to achieve and technically "free". I say "free" because of course we purchased all these things at one point for our home. However, for the purposes of these settings, I just shopped around the house and didn't buy anything new to add to the tables. These two looks could easily transition into summer (which they probably will!) and are easy to maintain.