Imagery in the Songs of Ascent - Psalm 120-134

The particle כ (like/as) occurs a bunch in these psalms, usually just the one or max two images throughout the psalm to draw out the point. Out of the 15 a third (120,121,130, 132, 134) don't have the particle, which does occur 15 times in the other 10. That said, there are some similes without the particle, for example 120:4, 121:5, 130:6, which, if you admit these, leaves only the the longest psalm, 132, and the final psalm, 134, without one.

Here's a list of the uses of כ, with my virtual similes in square brackets. (I've just used the NIV11 rather than providing my own translation)

[Ps 120.4 He will punish you with a warrior’s sharp arrows, with burning coals of the broom bush.]
[Ps 121.5 The LORD watches over you— the LORD is your shade at your right hand;]
Ps 122.3 Jerusalem is built like a city that is closely compacted together.
Ps 123.2 As the eyes of slaves look to the hand of their master, as the eyes of a female slave look to the hand of her mistress, so our eyes look to the LORD our God, till he shows us his mercy.
Ps 124.7 We have escaped like a bird from the fowler’s snare; the snare has been broken, and we have escaped.
Ps 125.1 Those who trust in the LORD are like Mount Zion, which cannot be shaken but endures forever.
Ps 126.1 When the LORD restored the fortunes of Zion, we were like those who dreamed.
Ps 126.4 Restore our fortunes, LORD, like streams in the Negev.
Ps 127.4 Like arrows in the hands of a warrior are children born in one’s youth.
Ps 128.3 Your wife will be like a fruitful vine within your house; your children will be like olive shoots around your table.
Ps 129.6 May they be like grass on the roof, which withers before it can grow;
[Ps 130.6 I wait for the Lord more than watchmen wait for the morning, more than watchmen wait for the morning.]
Ps 131.2 But I have calmed and quieted myself, I am like a weaned child with its mother; like a weaned child I am content.
Ps 133.2-3 It is like precious oil poured on the head, running down on the beard, running down on Aaron’s beard, down on the collar of his robe. It is as if the dew of Hermon were falling on Mount Zion. 

As you can see, a lot of these are quite poignant and emotionally rich images. There are obviously those four  exceptions in square brackets which have images but not כ, while there is only 132 and 134 without either a simile or the particle כ. There's really only 126 which has two separate images; 123 is saying more or less the same thing, and the ideas in 128 are closely related also. 131 literally says the same thing twice, leaving 133 as the only psalm which has a simile about a simile: brotherly closeness is like oil running down which is like dew falling on Mount Hermon (I'm not sure the NIV has understood the imagery here, but I'll leave that discussion until a post on Ps 133).

In short, when reading the psalms of ascent, keep an eye out for the similes/metaphors/images. Get to the heart of them and you'll get to the heart of the psalm.