We're heading to Europe with DS in May, and as he's quite full-on and never sleeps much we are also looking at medication to sedate him a bit. Don't want to have to give it to him, but we need that option if he's really playing up and wont sleep. He's quite a "challenging" little guy! My GP suggested Polaramine as DS is too young for phenurgan (SP?). The pharmacist wouldn't even sell me Polaramine as it's not advised for children under 2, however a different pharmacist had no issue with handing it over! Another option is Brauer homeopathic Calm remedy, which is completely natural. This, however, has little effect on my DS but chances are it would be more effective on other kids.
Here is a link to another thread similar to this one with a few ideas.