The Irish are loved here. I've only met a handful over the years and I hang out primarily at pubs, places that show football (soccer you dumb americans) and play football. I'd suggest Banker's Hill, Golden Hill, North Park or Middletown. You are more centrally located to downtown and everything.
Word of caution, any of your friends that are under 21 are going to have an issue getting into bars. It will probably happen more often than not, but you'll be able to get in sometimes, just don't expect to automatically get in everywhere. Irish girls are the best, hence why I date one, and everyone here is pretty accepting of the Irish.