Depends where as it is a bit of a struggle being 17. I've done quite a bit of travelling, most recently in Singapore/Australia and had to select hotels very carefully and used a few loopholes at times. Premier Inn are very accepting of 16+, Travelodge and many other branded hotels not so much. When I've stayed abroad it's nearly always 18+, in America sometimes it's even more. Check the terms and conditions as you can get into some sticky situations otherwise.