Good luck on your search!!! A few bits of advice I had were to check out the feel of the place - is it organised chaos, so lots of variety of activities present for the kids to do (easier to assess in toddler rooms) rather than just 1 set thing out at a time. Is the environment interesting vs sterile - with artwork etc on walls/ceiling. Are staff interacting with kids rather than chatting together? How do kids progress between rooms?
Also what are you getting for your money - sounds silly but the centres I visited had different stuff you had to bring. Some nappies/food/wash bedclothing at the end of the week and others just the child - may be worth factoring in all required rather than just the $$. Also you will get 50% rebate quarterly if you meet the roght requirements, maybe more CCB rebate also - worth checking out to factor in!
This is all so personal and about what works best for you - ask all the questions you can to help you decide. We are really happy with our cc experience and the staff are pretty much extended family!

Good luck!