We land at Belfast airport at 9am Friday and need to be in Letterkenny for 6pm, so have all day to explore!. We would like to see the Giants causeway, but any other suggestions please for any other "must not be missed" places. With 6yr old DD, by the way, thank you!
If you are using Belfast city airport then you could visit the Titanic experience in Belfast. Altho it is pre-bookable. You could drive up around the north antrim coastline which is quite beautiful. Stop off for photo ops at Carrickfergus castle. Carnfunnock countey park near Larne is a good stop for kids. Head around the coast to the Bushmlls Distillery tour, whitepark bay beach is pretty, Dunluce castle is a picturesque ruin, carrick-a-rede rope bridge is thrilling. Portstewart is lovely and has a really good ice cream shop, bakery and butchers shop on the front if you need provisions for your weekend. Londonderry is 2013 city of culture and has lots on. The tour around the city walls is very interesting. Have a wonderful time. :-)
Letterkenny is in Donegal isn't it? If you want to just see Belfast go to the Titanic centre as it is brilliant. I think you should also do a bus tour of the Troubles in Belfast. If not fussed about Belfast itself, Giant's Causeway and Antrim Coast beautiful. Take the coast road past White Park Bay and Dunluce Castle. Beautiful little fishing village called Ballintoy where you can eat catch of the day for lunch. Then onto Giant's Causeway after lunch. Derry is worth visiting too. You could do quick stop off before heading to Letterkenny.
Titanic Centre if you're landing at the city airport. Pre book the tickets online. 6 yr old will love W5, but you'd be there all day! Not get her out Drive up the coast road to the Causeway and see Carrick-A-Rede rope bridge on the way. And yy to Morellis for ice cream.