Great Idea.. Having worked there for 2 years in Jimbaran Bay (Intercontinental Hotel) I am quite familiar with the place. My brother has a house in Sanur with his lovely wife to be (April 4th, 2012) and 2 boys. I honestly have lost count of the times I have been but would have to be upwards of 60. If you need any help with the logistics don't be afraid to ask, I am sure many Perth bandits have spent many a holiday there as well would be only to happy to suggest places of interest.
I like the idea of private villas, however when travelling in large numbers (fingers crossed many will come) it may be best to either hire out a whole family run hotel (20 or so rooms) or look at a large resort. I agree Kuta should be avoided at all costs. If you must stay close by then perhaps look at Tuban or Seminyak. My pref is Lovina or Sanur.
Rob - I like logo # 2 and 4
anytime is a good time of the year - it will rain anyway so it doesn't really matter
As for flights - well it depends on where you are flying from - Air Asia are the cheapest as low as $150 return to $350 (and with the newest planes) Garuda - although older they have had some good specials out lately $298 return from Perth..Other carriers such as Jetstar and Virign go from Perth and are competitive. I guess it comes down to what time of the day suits you.. Last count there are about 14 daily flights to Bali.
If you check out
http://www.wego.com.au/ this is a search engine that will search all online travel agencies (wotif, lastminute, expedia, jetabroad etc etc) instead of searching 50 different ones. Also when looking at accomodation choices - you are never going to suit everyone and everyones budget - so I might suggest that you pick an area and let people choose where they would like to stay (perhaps 3-4 choices and diff budgets). You can then set up a central meeting point for activities and dinners etc ...
Newlife - As for Thailand - my other great love, I guess it depends on what you want to do and what time frame do you have? Do you want to party till dawn or relax or get some culture into you.. I spent 4 months backpacking around (incl visa runs) thailand in 07. There are many beautiful places away from the tourist traps like Pattaya, Bangkok, Koh Samui and Phuket.