I’ve done something myself recently and couldn’t find anything that good. I ended up building a simple one myself. Basically made a custom post type (just like pages) and each page is the username of a client. Then do some simple php to make sure the logged in username matches the page title.
You can also user peters login redirect to redirect users straight to their relevant page.
Of course, this only works with a single page for each client the way I have done it, but could easily be modified.
You now also have the [customer area](http://wordpress.org/plugins/customer-area/ “Customer Area / Client Area plugin for WordPress”) plugin provided your travel arrangments are either a page or a file. You’ll get it up and running in 10 minutes.