Belfast sight seeing advice please!

OK so this is completely unrelated to rats....hope that's allowed
I noticed some of you are in Northern Ireland and need a bit of advice, I'm bringing 3 teenagers to Belfast later this month (mine asked if we could go to the Titanic Museum and I said yes why not, not realizing "WE" also meant the other two that live in my house most weekends )
So far we plan to arrive at lunchtime(4 1/2 hr drive from here), go look around, Titantic experience, CS Lewis tour and some sight seeing, then stay overnight and go to giants causeway and head home late afternoon.
So is there any really cool places to bring teens?
They like history, books, music, but not big into shopping.
We would consider making it two nights if it was really worth it.
Any ideas welcome!

You have to book the titanic experience, just to warn ya. The ulster museum is pretty cool too, it's right beside queen's university and botanical gardens, so you could walk through there too. & The Giant's Causeway is well over an hour from Belfast, near 2 hours, so if you're considering it, I'd make sure you're up really early in the morning so that you can have a few hours before you leave. There's also bushmills distillery up there which is good, though I don't know what their policy is for teens.
Other things in Belfast, there's the zoo, it's nice. Parks and places, the usual really. Are you going to be driving? I can recommend parking, places to eat etc

PS. I'd suggest staying 2 nights if you're doing the Causeway. Stay up at the North Coast and go to Portrush too, there's loads of amusement places, a nice beach, Dunluce Castle's nearby, surfing, etc.

Thanks for reply, yes I will be driving, from south Kilkenny, so quite a drive.
Places to eat and park would be great, I looked up the zoo, botanic gardens and queens uni(one of the places my daughter considered for uni when she was younger, and yes she is 14!)
I was thinking the causeway was a bit of a drive so maybe the second night would be good, depends on cost and what they want to do.
We decided on Holiday inn(cheap and has a pool), and booking it now along with titanic tickets.
God knows what I'm letting myself in for, all that driving and 3 teens!
I've never been to Belfast so all advice welcome.
Thanks!