In his notes on Psalms Bonar demonstrates the importance of reading them "with your left eye on David and your right eye fully on Christ." Much like the Song of Songs this is a 'both/and' book.... though Scripture is always firstly about Christ, and only then applicable to us in Christ. Psalms are beloved for speaking to the human condition but they do more - they sing of the gospel (which of course makes them deeply applicable to all!).
As Augustine said, "the voice of Christ and his Church was well nigh the only voice to be heard in the Psalms... Everywhere diffused throught is that man whose Head is above, and whose members are below" Bonar says: "we ought to recognise his voice in all the Psalms, either waking up the psaltery or uttering the deep groand - rejoicing in hope or heaving sights over present realities." And Tertullian says we see the person of Christ in all the Psalms.
Here's a couple of examples from Bonar:
On Psalm 27 (p94 - pdf 109): "the Righteous One's confident assertion of safety when lonely amid surrounding foes"I look forward to more reading from Bonar, and others who've gone before us, as I prepared to preach on one of the Psalms later this summer.
"To see the Lord, in his temple where everything spoke of redemption, - there to see the Father's beauty, was the essence of his soul's desire. This "beauty" is the Lord's well-pleased look; such a look as the Father have, when his voice proclaimed, "this is my beloved Son, in whom I am well-pleased". It also means, all that makes God an object of affection and delight to a soul. Nothing could be more desirable to Christ than this approving look of his Father, teling, as it did, his love to the uttermost. And nothing to us sinners, can equal this look of love; it is the essence of heaven now, and heaven for ever. It is the "one thing;" for from this holy love proceed all other blessings. to catch glimpses of this "beauty" in the temple was our Lord's aim; he engaged in no other pursuit of earth. Neither did David..."
And on Psalm 63, which he calls "the righteous One finding water-springs in God":
"A Psalm for David - a Psalm for David's Son - A Psalm for the Church in every age - a Psalm for every member of the Church in the weary land! What assurance, what vehement desire, what soul-filling delight in God, in God alone - in God the only fountain of living water amid a boundless wilderness.... And when we read all this as spoken of Christ, how much does every verse become enhanced. His thirst for God! His vision of God! His estimate of God's loving-kindness! His soul satisfied! His mouth full of praise! His soul following hard after God!... And when verse 7 shews us the soul under the shadow of God's wings, rejocing, we may say, it is not only like as "the bird sheltered from the heat of the sun amid the rich foliage sings its merry note," but it is the soul reposing there as if entering the cloud of glory, like Moses and Elias"