Went last year and due to go again in April.
Southbank a must,Mount Coo Ta and the lookout pretty good.
Roma Street Parkland right in the centre also pretty good.
Head to the Castlemaine brewery for a tour and dont forget Suncorp.
We blagged our way in and got a free tour.Explained we had come from England and knew Alfie.

Australia Zoo (Owned by the Irwin family) is an hour or so outside Brisbane, but well worth a visit and I'm sure your kids would love it as well.

Stradbroke Island is decent as well, and you've got the beaches of the Sunshine Coast etc not too far away.

Loads to do in Brisbane itself as others have already mentioned, Southbank is quality, IMO one of the best parts of any Australian city.

Castlemaine Brewery also worth a visit. Its a stones throw from Suncorp, and the Caxton Hotel just up the hill would be a good pre match pub.

A bit out of the way but the Breafast Creek Hotel does amazing steaks if your anywhere near there at any point. Favoured by golf legend Greg Norman no less.

been to brisbane 5 times with having family there, imo probably the best city in oz, relaxed and layed back. brisbane beach, looking cross at the city skyline is a must, was the site of the brisbane expo, post office square, mount coot-tha gives a fantastic view of the city and how vast it is.

if you hire a car:-
surfers paradise-1 hours drive, if you stay over night checkout jupitors casino!
movie world, dreamworld, wet n wild all on way to surfers along pacifc highway

my favs were a drive upto the sunshine coast, seeing places like noosa heads, bribie island, you pass australia zoo going that way

been to brisbane before, i would definately reccomend visiting lonepine (think thats how you spell it) it's a bit of a koala sanctuary/zoo. great for kids. the australia zoo is a must...go see agro!!!

head up to the Gold coast for the seaworld thats worth a visit n you can entertain yourself looking at the meter maids while the kids play on the beach!!!

in brisbane there is the south bank, man made beach it's worth a visit great location and suroundings.

as has already been said the castlemain tour and a tour of the stadium is worth a go too.

the beer is castlemain, but i drank the NSW toohey's extra dry and it is a belter either that or pure blonde. you wont see fosters anywhere though ha!!

i think ther eis a warner village/park out on the way to the gold coast. whilst on the GC it might be worth while booking a seas fishing experience, i did and really enjoyed it!