I am considering purchasing airfare/car rental/ and an open voucher for BB in Ireland for an upcoming trip in June. Does anyone know if the open vouchers are worth purchasing? Do many BBs honor them? Thanks for any information or tips....

The B & B vouchers can work out to be cost effective. There are different companies you can by from each with it's own selection of B&B's that except their vouchers. Be careful as some towns may not offer any options or may only have 1 place that will take your voucher so pre- booking is advised, turning up and finding out no rooms are available can be a bit of a downer. Do a bit of research before choosing vouchers to make sure they cover each town you plan to visit.

I haven't used the vouchers, but generally, many travelers don't like them. They limit your choices quite a bit, as many B&B's won't accept them. A B&B makes more money from a paying customer, so their motivation will be limited if they have other potential guests.
As poster #1 suggests, be sure to book ahead if using the vouchers.