Two options that haven't been mentioned.
SPG has a single hotel in Dublin. You can use your points there and book with IHG in your other destinations. Check availability at Westin Dublin and IHG wherever before making any changes!
OR
IHG has an option to redeem points at other hotels. Click on "Rewards" and under the "Travel Anywhere" header there is a link to a hotel search. I have never seen these to not have 100% cancellation penalties and they are also very poor value. As it sounds like The Arrows and Circles Blog inspired this trip, you likely don't care about ongoing value.