If you're booking accomodation, DO NOT tell them you're a UK stag/hen party because all of a sudden, it's "Oh dear, fancy that, we're fully booked". They don't have a good rep here, I'm sorry to say.
Stag/Hen-friendly places would be either Club M in Temple Bar or Break for the Border, near Stephens Green or Trinity Arch on Dame St.
A lot of bars in Dublin City Centre will not let stag/hen parties in at all, so hide the plastic willies and boobies if you can.
Some pubs in Temple Bar even have signs up saying "No Stags or Hen parties", so you really have to be on your best behaviour if you want to go somewhere decent, otherwise you'll just end up in crap cheesy nightclubs with a load of other UK stags and hens.
If anyone in the party shows signs of "getting merry", they WILL be asked to leave - I have seen this happen a couple of times in bars (e.g. The Bank in Dame St).
There are loads of other things to do in Dublin, get out of the English colony that is Temple Bar and see the *real* character of the city :-)


