I am not taking luggage as am flying up and back the same day, so cannot help anyone. Guys, please work together here if you wish to take your banners, flags up for this one. If you cant check in your stuff, then give your banners to someone who can. Its not rocket surgery!
Here is some info i found from some of the major carriers. NOTE.. That the information below can only be used by those who have booked their flights with the allowance of being able to check in the luggage. If you have booked for the cheap flights with 'carry on' luggage only, then you are not entitled to this. If you wish to do so, then you will be charged by these companies in accordance to their excess baggage rates which you will find on their websites.
QANTAS
Australian Domestic* on Qantas flights (excludes QantasLink) No restriction on the number of pieces.
Total dimensions of each piece must not exceed 140cm (54in)
JETSTAR
Bulky items (maximum 1.9 metres for A320, A321 or B737 aircraft, maximum 2.77 metres for A330 aircraft), including but not limited to bicycles, surfboards, skis, golf clubs, snow boards, may be included within the allowance, subject to space availability.
VIRGIN
Virgin Blue and Pacific Blue fly a number of different kinds of aircraft, all of which have slightly different operational limitations which affect the weight and size of baggage the aircraft can carry. Accordingly, Virgin Blue and Pacific Blue may carry items up to 3.00 metres in length, depending on the aircraft type.
In all cases, Virgin Blue and Pacific Blue will make all reasonable efforts to transport oversized items on the same flight as you, but we cannot guarantee that this will be the case.