The widescreen guitar hook on Use Somebody is Matthew Followill — not Caleb, who plays rhythm and sings — riding a delayed octave melody through a Matchless combo. Producer Jacquire King confirmed the Matchless was the amp on this track (the Selmer was Sex on Fire's). The shimmer is a rhythmic Line 6 delay plus a lush studio reverb (an Eventide DSP4000 added the 'synth-like' sheen at Blackbird in Nashville). The guitar is dialed clean and bright, the delay and reverb do the rest.
Should reverb go before or after delay in your signal chain? The default order, why it works, when to flip it for ambient and shoegaze tones, and how to route both on a modeler.
Lock delay time, reverb predelay, and modulation rate to the same tempo and the whole ambient bed moves as one. The note-division math, a worked example, and how to set it on Helix and Quad Cortex.
When the delay is on the grid but the reverb isn't, ambient guitar smears against the beat. How to put predelay and a dotted-eighth delay on one tempo grid, with a BPM chart you can dial by ear.