I hired out a hall and had family, friends and family friends there. Lots of cheesy music and drinking
I had it smart dress too - any excuse to buy a nice dress!
It's all really about what you want. If you want to be centre of attention for the night then a party could be just the way to go. If you're more the type to go out on the town then why not get a big group together, get put on the guestlist of a local (or not local) nightclub. Turn up fashionably late, skip the queue and have a night out there.
For one of my mates 18ths, he's organised for us to be put on the guestlist for a big club in London and we're all chipping in to get a limo up there. 20 of us are going and it sounds like it's going to be a great night, even if it isn't til mid June
If you're not the party type, you could always have a nice meal out with friends or do something during the day - theme park, for example?
If you do want to hire out a hall or something you'll have to start looking EARLY because so many refuse to cater for 18th parties as there are always underage people there and they don't want to risk their licence serving 17 year olds. It helps if you get a parent on board to do a bit of persuading!
Good luck anyway, let us know what you decide!