Are these a wise investment? And for things I really want to do (I'm going in June) do I need to call or reserve a spot in advance? For instance i want to see the Kilmainham Gaol while I'm there. Do I need to reserve a spot if Im going in June. Anything else you recommend I reserve spots for in advance?
Firstly, you can not 'Pre-Book' for most Heritage sites -- particularly Kilmainham. It is best to get there early on the day to get a tour time. Even then there can be a substantial wait.
Dertermining if a heritage Card is cost-effective is difficult as it depends on how many and which sites you plan to visit.
Not all sites are covered by the Heritage Card. For a list, see: http://www.heritageireland.ie/en/
__________________
Bob
Help Us to Help You. The more you tell us about your plans (dates, interests, budget), the better we can tailor our advice to suit!
The site Bob mentioned will give you opening times, prices, etc. To determine if the card will be of benefit make a list of places you want to see, check prices and see if they add up to more or less than the card: http://www.heritageireland.ie/en/