I'm afraid to say that the professional advice is to individually stake each flower - the heads are often too heavy for the stems, and if not staked, end up on the ground. It's actually why I don't grow paeonies, I can't be bothered to stake. I know, I know, lazy, lazy, lazy, but its not exactly low maintenance, is it...

I use the metal half moon stakes for mine and find they work very well.

I grow many peonies and find the grid type work best, without going to the expense of buying single supports for each bloom. You must however introduce them early, just as the new shoot appear. I position the grid a few inches from the ground and as the year progresses raise the height as the plant grows taller.
The ones generally available in the shops, don't have long enough 'legs' for really tall varieties. Others are available and tend to be much more expensive.

what about a tepee kind of arrangement of long bamboo or canes and use some string or fishing line down to the branches or flowers you want to hold up ? I think the grid idea is bye far best but I guess youd have to hack your roses b ack and start again . just a thaught .

Thanks everyone for their advice. I'll try the grid i think