Spreadsheets, in my experience, are not the best choice for organizing data. If you want to keep things organized in another program, why not use a database instead of a spreadsheet? It's easy enough to create an Access database to contain dates, places etc, and then tap into that with a CGI script using DBI. Even better is using MySQL instead of Access. (MySQL is freely available and easy to set up.)

There's a wealth of information available here at perlmonks and on the web in general to help you get started if you aren't familiar with DBI and ODBC or databases in general. While a database might be overkill for your task right now, it might turn into something you could build on in the future.