We are going to Adelaide this year and looking forward to the Barossa Valley tour . No idea in evening , but I am sure someone will help you .

I’m not sure if it’s open at night but the Beach Hut (or Beach House) is fantastic! It’s in Glenelg & is like an arcade with mini golf & water slides!
Great fun for the whole family with the double carousel for young children as well.
Food I’m not sure on but I think there is a few small restaurants & cafes around the Beach Hut (or Beach House).

Contact the local council of where you plan to stay. Or the local visitors/tourist centre. They supply awesome information on the area, entertainment, eateries, free stuff etc And they supply this info free of charge. I’ve had envelopes full of pamphlets sent to me before

google it and check out trip advisor

there is an ice arena or dinner in the city and a stroll around looking at the sights (probably boring for teenagers)

Go visit the wineries. You are spoiled for choice 1. The Adelaide Hills, 2. Barossa Valley, 3 McClaren Vale. or go out to see The Rocking Horse in Birdville if you have children and call in to Hahndorf on the way back to Adelaide. This is a wonderful city.
PS Don’t forget to call in to Haigh’s if you are a chocoholic.

Boulderzone Indoor rock climbing is really fun challenge kids against parents. Open until 10pm. Go-Karts are awesome fun for all the family and there are some open until 10pm.

Google ‘Tourist Info’, or ‘night life’ or family entertainment’ in Adelaide. You will have hundreds of answers to read and choose from. Tourist sites such as Trip Adviser and the actual Tourist Bureau will be a boon of information. Let your fingers do the walking. The relevant info is based on which dates you are there, assuming you will be visiting, not already living there. It is the city of Churches. Go visit a different Church every night you go out, and eat at the closest food joint you you come across.

Not in Adelaide itself but manarto zoo is nice, yes I know you have teenagers but it is a pretty cool zoo, very safari like.