When I'm in the mood for something DT-ish but not DT, I reach for side projects of the guys in the band. I don't have much progressive music otherwise (other than Floyd, Genesis, and Rush, etc), so for me it's usually things like:
Neal Morse
Transatlantic
OSI
PSMS
Flying Colors
The Winery Dogs
Adrenaline Mob
Rising Power
Avenged Sevenfold
Mullmuzzler/James LaBrie
Frameshift
Winter Rose
Eden's Curse
Tim Donahue
John Petrucci
Liquid Tension Experiment
Dominici
Jordan Rudess
Just looking at this list, it makes me realise how much music you can get to listen to while still listing to any of the guys from the band! And most of it is still amazing, IMO.