We really enjoyed our short overnight stay at Phantom Ranch. Even though they had a rare plumbing break, and we had to use buckets to flush the toilets, it was still a very enjoyable stay. Everyone down there has either hiked or rode in, so there's a great sense of camaraderie.
The dinner was filling, with lots of carbs, and the sack lunch had lots more, plus the electrolyte replacement powder - good to know so you don't carry it down yourself, or skip the lunch if you've got enough power bars and trail mix already. (I didn't really need a white bagel and cream cheese, or a pack of Oreos and pretzels from the pack lunch, but the apple came in handy...)
The bed got more and more comfortable as the night wore on, the dorms were very clean, especially considering everyone was dusty from the hike.
In winter, there are creeks you have to cross on the Bright Angel trail back up, so consider waterproof hiking boots, just in case you slip off the rocks on the way across. And if you go in winter, definitely bring traction devices for your shoes, because you'll need them for the top two miles.
One last note: Indian Gardens was very cold in the morning on the way back up - depending on the whether, it would be better not to stop there for longer than your bathroom stop, otherwise you'll lose all the body warmth you generated on the first part of the hike.
Also note that you will get waken up by the 5 am wake up call for the first set of hikers, even if you have the 7:00 am breakfast, not the 5:30 breakfast.
Very nice and accomodating staff, too.