DD likes to go see the "Live Crib" outside the Lord Mayor's House, which is followed by a little bit of shopping (mainly wandering to look) and ending with a hot chocolate and a bun in a nice coffee shop looking out at the shoppers. (I don't do any of my shopping that day, and try to have most of hers done too beforehand so we don't need to get much or carry much).
We went to Green Santa in Belvedere House last year, a huge hit. You go through the wardrobe door into the snow forest in Narnia, where there are trees and a few animals, before the Elf calls you in to meet Green Santa (in his green robes). Child plants a tree with Santa, visits with his pet hibernating hedgehog, talk a bit about nature and minding it, and he sends you on your way with your tree, a tub of wildflower seeds and you choose a candy cane off his tree. (You can take photos if you want but not photographer there).
We also love the Santa Train, a steam train from Dublin to Maynooth with Santa on board visiting the whole length of the train. There's also a wandering group of carol-singers with a guitarist. Each child gets a selection box, adults can get a mince pie and coffee/mulled wine from dining car. And plenty of train memorabilia (including lots of Thomas) from the on board shop. I know it runs from Belfast as well. (It's especially lovely if you get the last trip of the day and run back along the frosty canal into the city at dusk, with all the lights on!).
DD also loves just a trip in the car with a travel mug of hot choc, snuggled up under her rug, after dark, when we do a look at all the Christmas lights on various houses in our area. Some do a big show, and we look out for good ones in the weeks beforehand and try to pick a route to get some lovely magical lights.
I like to keep Christmas Eve relatively free as well. DD usually comes into work with me for an hour or so (if I don't show up, I have to take a full day off), we meet DH for coffee/brekkie/lunch on the shopping street (only 5 mins from my office) and any last minute bits. Then we head home for some family fun - a walk on the big hill near us and burn off some energy in the playground, maybe the cinema, watch a dvd with the fire lit (somehow that one escapes DD!! But Santa is magic, and she's seen in "The Santa Clause" how he can put out fires if need be), wrap any presents together we need to. Sometimes we have visits to do, and I might potter around doing a few things, but they are all things I can abandon.