You have a decent sized layover in DFW. If you plan to get a rental car, there are hotels thru-out the area that will be better priced.
There are 2 Hyatts at DFW. Both are physically within the airport (not simply located near the airport).
The
Grand Hyatt is the newer (and pricier) of the 2. If arriving from SYD on the non-stop, you'll be arriving Terminal D and the Grand Hyatt is actually a part of that terminal. Once clearing Customs, proceed as if you're exiting (you don't physically exit the building, I'm saying that you don't want to proceed back into the "secure" part of the terminal as if you have a connecting flight). Just follow the signs to the escalator or elevators (lifts
) to the Grand Hyatt.
If arriving from another terminal, then things are a little trickier. The Airport Train is the easiest way between terminals, but it is located "airside" (within the secured area). If you have carry-on luggage only, walk off your plane, find the Train and go to Terminal D. But if you have checked luggage then you'll be going "landside" to claim it and can not return thru security. In that case, you'll need to catch the hotels shuttle bus downstairs.
The
Hyatt Regency is a nice enough property. It's nowhere as nice as the Grand, but sometimes the price increase for the Grand is not (IMHO) worth it. Some days (typically weekends ??) the price difference isn't so bad. The Regency, while located among the terminal buildings, is not on the Air Train's route. You can walk there from Terminal C, but it involves an akward, poorly marked path through a couple of parking garages. I recommend the shuttle bus.
Go thru the Sticky:
Hyatts - Property Index & Reviews on Flyertalk thread and you'll find the link to the review threads on both properties. You can then decide for yourself if you think the higher cost for the Grand is justified.
Departing the hotel for your outbound flight is almost everything in reverse, with some exceptions if flying on American (AA).
Regency: take the hotel shuttle bus. If on AA, you can walk to Terminal C, check your luggage, go thru security, then take Air Train if your flight isn't Terminal C (AA is in almost all terminals at DFW)
Grand: (remember: Terminal D is where the Grand is located) AA has check-in counters in Terminal D (D is the "international" terminal but does handle domestic flights, so there are no restrictions on entering it). You can also enter via terminal D when flying other airlines if you already have your boarding passes and only have carry-on bags with you. If you need to get boarding passes and/or check your luggage, then go downstairs outside and catch the airport's Terminal shuttle bus to your terminal.