Timelessness of Design

I have to admit, this post at Apartment Therapy has me freaking out a bit. I don't want to break our backs fixing up our house only to have it get trapped in time, like my grandparents' with its pea green wall-to-wall carpeting and dark wood paneling. I don't tend to have very trendy taste (I don't own a single pair of leggings), but I am concerned about my habit of reading design blogs that are full of alluring stuff that I will likely cringe over in a few months.

I always said I didn't want to emulate my parents and have a house full of antiques and flea market finds that guests/children fear sitting on, but in my older (wiser?) years I'm leaning that direction. I want a functional and visually pleasing home that adapts as we grow and change, but I know S would agree that we don't really want to spend all of our money on constantly updating trendy crap.

That said, does anyone have any thoughts about what looks, pieces and elements are timeless and will endure our whims? Here are some of my thoughts:

Timeless: Ceilings and trim/moldings painted white or cream. May not be exciting, but you can't go wrong.
Temporal: Basically any other color on trim & ceilings, with a few exceptions when executed the right way in the right space. Like this.

Timeless: Natural and utilitarian materials like cotton, wool, leather, linen, natural wood, jute, galvanized steel, etc.
Temporal: Natural elements that are rare or exotic, like zebra wood for example, and cheap imitations like fake fur, faux bois and particle board. And plastic. I hesitate to buying anything made of plastic, because I'll probably get sick of it.

Timeless: Live, potted plants
Temporal: Floral prints, and really any graphic print. I keep thinking of the 90s when sunflowers and daisies were everywhere -- a good reminder to refrain from upholstering or wallpapering anything in a loud print, even if I love it at the time.

Timeless: Family photos and homemade or friend-made pieces as art
Temporal: Art in the form of signs, sayings or random letters, plus anything you bought that didn't have a genuine personal meaning.

Timeless: Items you bought on your own travels to interesting places
Temporal: Items that you bought at Target that were made to look like they're from faraway places

Timeless: Pianos / writing desks
Temporal: Rooms designed around electronic equipment or surround sound / computer desks

Timeless: Nice, well-made solid wood furniture from basically any era or style
Temporal: Having all the furniture in a house or room reflect a single style or time period (example: all mid-century modern, or all Asian-inspired, or all Victorian, etc.)

Here are some examples of what I consider to be "timeless" rooms that match my style; in other words, the details may reflect some trendier elements, but overall they don't necessarily remind you of any particular decade. If you switched out some pillows or lamps or artwork, will they ever really feel out of style?

Via Apartment Therapy - very neutral but easy to update:

Via my absolute favorite interior designer, Atlanta Bartlett (she has great name too!):

Via Remodelista - may not be everyone's taste, but certainly not "trendy":

Anyone have anything to add?