The Priority Pass-eligible lounge in Terminal 1 is named Skyview, and doubles up as the Business Class lounge for several airlines - Cathay Pacific, Air France, KLM, China Airlines, Delta, FinnAir, Bangkok Airways, Air Mauritius and Air Asia's Red Carpet.
The main lounge area is upstairs in a fairly secluded area of T1. It's open air, and although you do get a little spill-over noise from the rest of the terminal that's offset somewhat by a more airy / open feel, coupled with views of other passengers walking by.
For passing time there's a pretty good collection of magazines and newspapers available. This main area of the Lounge has a pretty nice number of tables, sofas and chairs (many of which have power points nearby). If it's crowded you can actually head to the second area through that bright doorway in the far wall ...
... to reach what I would consider a brighter, quieter and more aesthetically pleasing lounging experience. The corridor on the right leads to the washrooms and the showers (which could be insanely useful, or not at all, depending if you're departing from or in transit in Singapore).
Heading back to the main floor - there's a small buffet line with some cold cuts, salad, limited selection of hot food and satay. To be honest the selections on offer didn't really look all that appetizing. In a less ... accomplished airport (like New Delhi, or Nairobi, or Karachi for example) it would be great, but Changi is such a great airport that you'd get better grub at practically any other restaurant/eatery.
Besides the buffet line there's a coffee machine and some instant pot/cup noodles ...
... and a free flow drinks bar with soft drinks, juices and some wines and alcohol. I imagine the more alcoholic amongst you would appreciate bottomless drinks!
Being teetotallers, and having just eaten a substantial dinner, we settle for just a few sticks of (mediocre) satay, chicken flavoured cup noodles, two cans of juice, and settle down to wait for our flight. Do note that this lounge doesn't do boarding announcements so you need to keep an eye on the clock on your own.
Overall, Skyview is a decidedly mediocre lounge in the world's best airport - definitely not worth purposely coming to the airport early for, and most definitely not worth it if you have to pay (via Priority Pass). But if you've got a long transit, need a shower and a drink and some food, you'll probably be pretty satisfied!