Lansdowne Road is currently being redeveloped, and will be out of commission as a venue for the next few years or so (anyone who went to the old stadium will understand exactly why redevelopment is required). The RDS is certainly a possibility, although Bon Jovi can definitely attract a much larger crowd than the venue's maximum capacity (around 35,000 or so) - of course there'd be nothing stopping them playing more than one show, but I don't see this happening. However, although they didn't quite sell out Croke Park in 2006, I still think it's the more likely option.