Similar in meaning:
* Sluggish
* Lethargic
* Drowsy
* Listless
* Indolent
* Enervated
* Torpid
Similar in sound:
* Sanguine
* Angular
* Langorous (a less common synonym)
* Luminous (though the meaning is different)
Words with a similar feel:
* Slow
* Relaxed
* Gentle
* Dreamy
* Soothing
* Tranquil
The best word to use depends on the specific context and what you want to convey.