May I have good recommendation of accomodation in Canberra?

The Hyatt Hotel Canberra is definitely your best choice for Floriade - walking distance across Commonwealth Bridge, plus bus access into the city if you don't want to walk it. Also easy access by bus or taxi to Manuka or Kingston for good dining. The best choice would be to rent a car - the guys at the concierge desk at the hotel can organise it for you, or else you can pick it up in the city or at the airport on the way in. Have fun!