Joe, here's a label for you to check out:
Fat Possum Records
http://fatpossum.com/featured-artists/SO MANY GREAT GUITAR BANDS, new stuff, rather popular as it pertains to the alt-rock scene which is alive and well. Many of the new artists on this label are paying tribute to past sounds with modern twists on them.
They also have done justice to some forgotten and not so forgotten artists and bands with re-issues.
I also agree on the Ed Sheeran tip; probably the best example of guitar-centric pop out there right now.
As for the One Direction nod I made before; I have to admit that my attention turned that way with this specific podcast episode where the hosts reveal several Beatlesque tidbits in the One Direction song, 'Olivia':
http://www.tuner.show/episodes/2015/11/22/5-if-i-needed-some-one-directionThat Tuner podcast is one worth listening to. I'm disappointed they haven't made any episodes for some time, but it's a great resource for songwriting and for uncovering what makes pop-tunes tick with us; often revealing a sophistication that otherwise goes unnoticed.
Some other new to 15 year old bands with guitar-heavy sounds in my regular listening rotation (I realize some of these are in sslecta's list):
The Black Keys
The Hold Steady (careful here, mostly drug and drunkenness lyrics, but dang what a great sound)
Band of Horses
Coldplay (earlier stuff)
Bruno Mars (for funk-guitar)
The Shins (they get my vote for the most interesting vocal melodies, and their rhythm guitarist is very inventive - if you have girl students, make sure to introduce them to her)
St. Vincent (female indie-rock-star extraordinaire, with a signature Music Man guitar that is super cool; she has some very riff-heavy songs)
The White Stripes (some of the most recognizable riffs of the past 15 years - you know it when you hear them at baseball and hockey games to rev up the crowd - I know many people don't like Jack White, but sorry - try to get the riff for Seven Nation Army out of your head once it's in there)
And as a guitar teacher, besides all of the comments about teaching reading of music which I agree with; have no shame in teaching them old school rock. Some of those kids wearing the fake faded out Led Zeppelin, Pink Floyd, AC/DC T-shirts actually are listening to that music.
Radiohead
Arctic Monkeys