We have a layover in Brisbane and wanted to know if they have any tours that leave the airport for those that are on a layover. when we went to Singapore they had one
I doubt it. Singapore is a major international hub with huge numbers of pax connecting everyday. Brisbane isn't. Just can't see there being any demand.
How long is your layover and do you have a visa to enter Australia? Are you transiting international to international on one ticket or some other transit?
So if it’s all on one ticket, your bags should be checked through. You’ll need to clear immigration, quarantine and customs (with your carry ons). Might be quick might take an hour. You need to be back 1.5-2hours before your next flight, so around 3hours or so to spend in Brisbane.
Was there anything in particular you fancied trying to see in Brisbane? There is a train from the terminal into the city centre. Depending on your interests you could do a few things before heading back. You will need ETAs though (assuming you have US passports)
Only three hours is not much. You could catch the Airtrain to South Brisbane ststion and walk around Southbank (beautiful gardens and lovely river/city views) and catch the train back either from the same station or another depending on where you plan to walk. Other options you would have time for are Roma Street Parklands, GOMA and or Qld Art Gallery, or a ferry from Southbank downriver to Hamilton and then a taxi back to the airport.