First of all I don't recommend you start with hotel booking application. I have done one in PHP and worked on one made in JAVA and both of them were complicated. I suggest you start with something easier. You could, for example, make a script like IMDB for your own movie collection. It has all the features that almost any other application will use. You have a database that you have to manage (add, edit or modify movie data), image editing for covers and thumbnails, user management for movie ratings and other stuff (for family members or even public, so you can have different user groups etc...), and many other things you can add. That would be a good way to start and it is useful too
In any case you should definitely consider using some PHP framework. I can't imagine working on a complex PHP application without using some kind of a framework. I personally like CodeIgniter but this is a question of personal preference. You can choose another one if you like and here is a handy list of PHP Frameworks you might like http://en.wikipedia.org/wiki/Comparison_of_Web_application_frameworks#PHP
Good luck and remember, practice is king!