In Whippany, NJ (west of Hoboken, NJ/ NYC area) there is the Hanover Marriott Hotel.
They have an Irish pub, called The Auld Shebeen, that might meet your needs for a contained hotel/ eatery event.

This place in Lancaster looks like fun:

www.fultonsteamboatinn.com

I've actually eaten at the Auld Shebeen and really enjoyed it. Apparently, a 400 year old pub was dismantled in Ireland and transported to the US , where it was reconstructed. The place really has a lot of atmosphere, and the hotel is quite nice too. Not too inconvenient to get into NYC for sightseeing too!
Good luck!

The Joseph Ambler Inn in North Wales (PA) is a lovely spot; you may be able to take over the whole place: www.josephamblerinn.com

Having lived in Bethlehem, PA and raised 3 children there, hands down I would choose Hotel Bethlehem. http://www.hotelbethlehem.com They have facilities to accommodate a variety of banquet sizes, and lovely shops right nearby. It's small enough that your group would still have a personal experience. Behind the hotel is an historic park with stroller/toddler access and plenty of room to play.
Depending on how many small children there are, tops for a group getaway is the Glasbern Inn, http://www.glasbern.com/. Glasbern Inn is simply a wonderful place to host an event. Definitely worth considering both of these.

I don't know anything about the restaurant, but I live nearby and why anyone would want to stay in Whippany is beyond me.

Hi NOconnor,

My name is Jessica and I work at Visit Bucks County, the official tourist promotion agency for the county. I saw your post and wanted to share a few suggestions for places to eat and stay in Bucks County.

Since you have family of all ages coming with you, Peddler's Village is a great place to set as your homebase. It's a village with 70 shops, six restaurants and a hotel on premise called the Golden Plough Inn.

Additionally, you mentioned you're looking for somewhere with history or an Irish-theme. Starting on February 1, Washington Crossing Inn, a restaurant in Bucks County, is hosting Irish Night every Wednesday. This restaurant also has historical roots because it's located where George Washington crossed the Delaware River in 1776. There are several hotels located in the area, as well.

For more information, feel free to visit our website (http://visitbuckscounty.com) or email me directly at jlawlor@visitbuckscounty.com.

Hope this helps you in your planning!

Jessica

Knobel's Grove is a great place for an all age family reunion.
I think there are quite a few good lodging places within 10 miles. My kids always loved going there and they have gone back as adults. http://www.knoebels.com/family-reunion.asp
There should be many improvements this spring since they did have a flood last fall.

I've stayed at the Fulton Steamboat Inn and it's actually a great hotel and might meet your needs (re the kids) because they have rooms with bunkbeds. Not sure if the restaurant would be what you're looking for, however.