Zoolights is at the Point Defiance Zoo and Aquarium off of Pearl Street in Tacoma and at the Front Gate it is $10. If you are looking to save some money but are not a member of the zoo it is online or at Fred Meyers for $8.50, although if you are a member it is only $5.
Personally, I loved seeing the pseudo Northern Lights along one of the pathways because of how pretty the colors work together and how nice it was to look up into. I also really enjoy the lit up trees in such Dr. Seuss fashion using colors such as greens paired with purples and reds paired with white. Another really nicely done part of the lights was outside the aquarium is lit up fish that look like they are jumping along the stream though they are still light, not to be confused with the moving light display of fish near the lit up display of bears.
Sadly, I had not bundled up as much as I should have in only a light jacket, it ended up getting a lot colder than expected. Since the aquarium was really the only place at the zoo that was heated and only place with restrooms it causes it to be quite packed with families and strollers. I still recommend making your way through the aquarium but maybe before the lights turn on or before it gets too chilly to avoid the large crowds.
I recommend bringing some snacks and bottled water while you are there especially if you plan to go as a group as food can be expensive. I also advise bundling up to keep warm, hats, warm jackets and gloves should be a must. If you are in a group or even by yourself, commemorate your time by taking a picture in the shark mouth inside the aquarium.