Obviously, the best place on the island, given that I used to live there!
Seriously, it has a lot to recommend itself, including a beautiful old ruined castle -- wander in and have a look, if the door is locked (and it isn't often), then you can get the key at the Post Office. Sad to say the tower on your right as you look at the front is closed off -- it's actually really well preserved inside, we used to climb in when I was a kid! The castle is constantly being stuck back together, if you go and see it and there's no scaffolding, you are extremely lucky! I should say, however, that the worst of it seems gone now!
Lochranza is, to quote the guy who owns the land, 'a deer farm'. This means that deer wander freely around the village. Please do not think that this means that they are tame. Keep kids close, as deer are very strong and could hurt adults. The general rule is that if you don't bother them, they'll not bother you, so don't get too worried. The photo below was taken in my back garden. You may notice that the houses in the village have very high fences -- deer and sheep (which also wander aroudn the village) can make a lot of mess of your garden, and deer can jump very high -- hence 6 foot fences. The village also has a lot of red squirrels and there are seals over on Newton Shore (the side of the village that the main road is not on) at low tide.
The main attraction in the village is the distillery, though it's not really distilling anymore. The visitor centre is great, very much better than most. You can try the whisky at the end if you want -- on the tour I did only one out of four of us actually tried it! I'm told it's very good though. There's also a nice restaurant.
Lochranza has a nice, brand new pier, which means the Waverley (last sea going paddle steamer in the world) might call in this summer. The old pier fell down and was finally removed around 15 years ago (I'm not sure on dates, I was a small child then!). For many years the steamers were the main means of contact between Lochranza and the world -- one old lady in the village, who was born around 1900 was 15-years-old before she went to Brodick, though she'd been to Glasgow, Tarbert, and Cambelton by steamer. The roads were terrible then, and still are, if your car has low suspension be very careful on the Arran roads.
Arran is a wonderful place for golfers - seven courses, one of which in Lochranza. Few of the locals play in Lochranza these days, so you'll get a round no problem, though you're cheaper to play elsewhere, such as Corrie or Machrie, both lovely courses.
If you're into arts and crafts, then Lochranza has two wee art galleries, one shows what the owner produces, the other (Castlekirk) has exhibitions now and then. Worth a visit if you can stand the walk is the Whins, above Newton Shore, very well signposted. The Arran Stonemen live there! You can get stonemen elsewhere, most tourist shops on the island, but you don't get the view without the walk.
The local village shop sells souvenirs for the tourists and groceries and newspapers, etc. for everyone.
Accommodation - the youth hostel in Lochranza is one of the best in Scotland so I'm told, and there is no shortage of B&B accomodation, and a nice hotel with a pub and very good bar meals, all homemade, down to the coleslaw and tartare sauce -- something you appreciate even more after moving to the mainland and being presented with chain pub plastic 'food'!