More films like this?

I'd probably include a couple of Jim Jarmusch films as well, such as Mystery Train, Down By Law or his Coffee and Cigarettes shorts. They would seem to fit neatly into this category.

Also I can't recommend Sympathy for Mr. Vengeance highly enough. Even though it's quite a violent film at times, it also has a unique, wonderfully original pacing to it, and is DEFINITELY chock-full of astonishing imagery. A breathtaking piece of poetry if you ask me, and definitely the best of the lot in Chan-wook Parks revenge trilogy. Although Oldboy and Lady Vengeance are also very good indeed, particularly the former.

Not sure if they all fall exactly into the category of what you're personally looking for, but I'd also recommend Donnie Darko, Eternal Sunshine of the Spotless Mind, Life is Beautiful, The Straight Story, Sideways and, of course, 2001: A Space Odyssey.
If I had to give you a bit of local, Danish flavour I might recommend you "Arven" (The Inheritance).
So, just from the top of my head, some additions to the list might be:

2001: A Space Odyssey (1968)
Jeder Für Sich und Gott Gegen Alle (1974)
Down By Law (1986)
Mystery Train (1989)
Life is Beautiful (1997)
The Straight Story (1999)
Donnie Darko (2001)
Sympathy for Mr. Vengeance (2002)
Arven (2003)
Sideways (2004)
Eternal Sunshine of the Spotless Mind (2004)

EDIT: Whoops, you already included The Straight Story yourself =) However, I'd recommend you to check out Jeder Für Sich und Gott Gegen Alle if you haven't already seen it.

"Nachtgestalten" is my personal favorite, kind of like "Alice in the cities"-feel to it.

A Swedish Love Story (1970)
Cría cuervos (1976)
Streetwise (1984)
Show Me Love (1998)
35 rhums (2008) -- or any Claire Denis

Great list. I'd add the following...

Late Spring (1949)
Pather Panchali (1955)
Winter Light (1963)
The Girl on a Motorcycle (1968)
Medium Cool (1969)
Why Does Herr R. Run Amok? (1970)
Kotch (1971)
The Last Picture Show (1971)
Two-Lane Blacktop (1971)
Cries and Whispers (1972)
The Mirror (1975)
Picnic at Hanging Rock (1975)
Bound for Glory (1976)
Heartworn Highways (1976)
The American Friend (1977)
Who'll Stop the Rain (1978)
Out of the Blue (1980)
Gallipoli (1981)
Montenegro (1981)
The Loveless (1982)
Americana (1983)
Stranger Than Paradise (1984)
My Life as a Dog (1985)
The Sacrifice (1986)
September (1987)
The Double Life of Veronique (1991)
Highway Patrolman (1991)
Rambling Rose (1991)
A Perfect World (1993)
Cold Fever (1995)
Smoke (1995)
Dream with the Fishes (1997)
In the Mood for Love (2000)
Rivers and Tides (2001)
Talk to Her (2002)
Whale Rider (2002)
The Brown Bunny (2003)
Nói albínói (2003)
Open Range (2003)
Spring, Summer, Fall, Winter... and Spring (2003)
Bubble (2005/I)
Brokeback Mountain (2005)
The King (2005)
Shopgirl (2005)
Encounters at the End of the World (2007)
Into the Wild (2007)
The Wrestler (2008)
Meek's Cutoff (2010)
Martha Marcy May Marlene (2011)

A lot of strange things happen in this world. Things you don't know about in Grand Rapids.

River's Edge (1986)

Wanda Nevada (1979) with Peter Fonda and Brooke Shields.

Radio On (1979)