The Adelaide Hilton is well located on Victoria Square with a bus stop across the road to catch the free city bus that will take you down the main road (King William Street to the Adelaide Casino). Also across the road is the Glenelg Tram which is a beautiful old tram that will take you to the beach (although Adelaide has some better beaches in my opinion but this one is easy to get to).
I stayed here two nights ago and I was upgraded to the Executive floor with a corner room. It is a nice hotel but a little dated. This is more than made up for by some of the nicest hotel staff in Australia (Australia in my opinion has the best service industry staff in the world).
I arrived at 8:15PM and the lounge closes at 8:30. The guy in the executive lounge said "No Worries - whattaya drink?" I said beer and 5 minutes later he brought a tray with three ice cold South Australian Coopers beers to my room. No charge.
For breakfast there was an excellent selection of fresh fruit, breads, hot breakfast, and the rest. The morning lady was excellent and made everyone feel at home.
The only shortfall is the excessive internet charges to use the internet in the lounge. Other than this, you could do a lot worse but not much better elsewhere in Adelaide. Yes it is a 1980 built hotel but the people really make this place.