Attending a wedding in Belfast in June with children - any suggestions for an extended trip?

You will be close to Newgrange/Bru na Boinne, which is south of Belfast. This is a fun and fascinating historical area that will allow the kids to move around outdoors as well as see sights indoors, so that could be a one day stop on an extended trip for sure.

Are you interested in heading south and touring the Republic of Ireland?Or are you considering including other countries in the UK or continental Europe in your travels?

I'm considering either, or both. My kids want to go to Italy and they like the beach. I thought I could even work both in. Do a few things in Ireland and then tack on another country. Unfortunately no one in my family is big into sightseeing so I am trying to think of things that would be interesting for them and provide them with a cultural experience. I realized that the TT motorcycle races are at the Isle of Man the week before the wedding, but I think I'm too late to get accommodations for that. My husband and kids would be interested in that. They are big into cars, motorcycles, boats, etc. Not so much green grass and sheep :(

My kids want to go to Italy and they like the beach.

I would be careful to calibrate your expectations for "beach." The beach you find in Italy may be (probably will be) very, very different from the beach you/they picture.

IME Americans who have never been to Europe generally have a very different idea of what a "nice beach" is compared to most European beach experiences (at least those that are easy for first-time tourists to get to). There's lots of great things to see and do in Europe. IMHO it's often a waste of time and money to try to do many things there that are familiar from at home - "a great beach experience" being a good example.

no one in my family is big into sightseeing...They are big into cars, motorcycles, boats, etc.

Hmmm. This may not be a problem you can solve. Europe isn't for everyone, some people would rather go to other places, do other things. And that's OK. Vive la difference. Maybe a tour of the Guinness factory - assuming they are open to things that are a bit different from Budweiser. Actually, that might be a good litmus test for you: bring home some Guinness, see how that goes over. If they sneer and want no part of it whatsoever, maybe a trip to Orlando would be a better use of your time...

Good luck.

Id include a day trip to giants causeway and Carrick a reed bridge

I was in Ireland in July with my 12yoa son. Dun Luce castle (featured in a RS episode) was fun to nose around in. Newgrange was cool. If they're into beaches, maybe a couple of nights in Portrush? Further west is the start of the Wild Atlantic Way, which might be fun for the car enthusiasts. I'm sure you can find a car show or motorcycle rally. I wouldn't know where to look for something like that.

One of the things my son enjoyed the most was just seeing the ways that everyday life is different there. And the same. Everyplace we stayed seemed to have a different type of shower, for example. We were in AirBnBs, so we were in the grocery store every couple of days, checking out the crisp (chip) flavors and the candy. And we tried HP sauce on our chips (fries). The cuisine in Ireland, much maligned by gourmands, is ideal for tween and teen boys--lots of meat and potatoes with mild flavors. And I found the prices (both restaurants and the grocery) very reasonable. And they can go to the pub with you (until, I think, 9pm).

If your boys like to read at all, I have a book suggestion. Bog Child by Siobhan Dowd is a young adult novel set in the early 80s on the border between the North and the Republic. We all read it and really enjoyed it. The story is engaging, and it can start a discussion about the Troubles. You know, or not. Also, it's a YA book that isn't just for girls. I find it's hard to find books for boys this age that I am also willing to read.

I'll add my two cents for what they're worth...There is much to do in Northern Ireland especially if you like to be active, which with an 11 and 14 year old I imagine you might. A trip up the Antrim coast is a must. You can walk across the Carrick-a-rede rope bridge with waves crashing below and take in the incredible Giant's Causeway. On your way you could take a trip to Rathlan Island off the coast of Ballycastle. There's Carrickfergus Castle and Dun Luce Castle as well. Some of the most beautiful beaches (although it will be cooler than in the USA) are up north near Colraine. If you are a Game of Thrones fan much of the series was filmed in Northern Ireland. In Belfast itself there is the Titanic Museum which takes one through the history of Belfast and its industry. There are a lot of sporting events in Belfast from Rugby to Football (Soccer). In Omagh is the Ulster American Folk Park. If you are interested in St. Patrick there is a great visitors center in Downpatrick and a visit to Saul church is a must. And the Mourne Mountains are a sight to behold and to be hiked. And they are on the coast so there is a beach. And Tollymore Forest Park is down that way as well. There's so much to do and see. I hope you enjoy your trip!

In Belfast proper visit the Crumlin Road Gaol (prison) and the Titanic Museum.

Outside of Belfast this might be a spot to keep the boys entertained https://www.colinglen.org/activities/skytrek-high-ropes/

I agree with Antrim Coast. Lots to see and do with some great walking opportunities. Public transport is fairly convenient.