Located inside the SLS, Northside Cafe is the only restaurant open 24/7 with a wide selection of American and Chinese foods. It's located right across from the pool entrance and also next to the other Chinese restaurant. Entrees are on the expensive side and the taste quality doesn't match the $$$ tag. The room service food you order come from the kitchens inside Northside Cafe.
Ambience (4/5): Restaurant is very sleek looking. Cafe was never empty the two times I was there, tons of occupied tables. There are both large booths and small tables for any party size. Great place for people watching too, as you get get all sorts of people walking into grab a bite.
Food (2.5/5): I ordered the beef chow fun and the Char Su buns. Beef chow fun had a great taste despite there being way more vegetables than actual noodles and protein. The char su buns was a disappointment though. Despite its high price point for two small buns ($6), the buns were not made in-house. Most likely ordered from a frozen food purveyor. the bun texture was very doughy and didn't have much meat inside.
Service (4/5): Table was not very clean when I was seated. I had to ask one of the staff members to wipe it again. Otherwise, service was excellent.
I would definitely try Northside Cafe again if I find myself on the North side of the strip late at night. I would just stay away from the Asian menu/selection.