hi,unfortunately cant give you any personal experience as im not due to give birth for a couple of weeks BUT .... i think this would depend on ''your'' thoughts and feelings on why you ended up with c-sections.perhaps if you feel you could have been helped with different positions/less intervention or more time etc then it would be perfectly acceptable to make the changes you want to and create a different birth plan this time around.also how did you feel about your cs....recovery etc.
There is a yahoo group for people considering vbac I think - try http://groups.yahoo.com/group/ukvbachbac
Obviously you want to put your own and baby's welfare before your own personal interest, but, if all is going well, then it is safer for babies to be born vaginally so, by doing lots of research, you may well find that by choosing a vbac, you are actually putting your baby's and your welfare first anyway.
It's not as if they won't monitor you a lot during labour so if anything looks the slightest bit worrying, they'd give you a caesarean anyway. At least if you start labour naturally then you know the baby's ready to be born.