I agree Maggie, they will be too warm in the summer however when it's that warm - or at least in our house cause we don't have central a/c, DS sleeps in normal pjs - either shortie pjs, a singlet and nappy or long sleeved/legged ones, depending on exactly how hot/cool it's going to be.

Last night here in Melbourne DH put him just in a pair of flannelette long sleeve/leg pjs and he was fine. He did wake about 5am. Not sure if he got cold or just work (he does that when he's overtired and was late to bed last night which will always have him waking overnight). I just give him his toys, and I did pull his doona up, but I'm up already this morning(obviously) and DS is still asleep and he's kicked off the doona and is still happily sleeping.

Other than that, the polar fleece ones have been an absolute blessing in our house. I know in wintertime, places like Target used to sell tracksuit type fabric (not polar fleece though) all in ones like the blanket sleepers. Maybe these would be better for the warmer months - but obviously harder to get at this time of year.