how do I allow visitor to filter content of post?

I have a travel blog website already set up with a number of categories and what I want to add is a means for the casual visitor (i.e. no registration or profile required) to select the kind of content they are interested in. In my case, this would have the effect of removing identified paragraphs within a post. Effectively, I see this as multiple filters common to all existing categories.

My approach so far is to add a sidebar multi-select dropdown menu which specifies all the filters. When this is submitted, FROM THEN ON, I want all posts requested by the visitor to be subject to these filters.

This is where I am hoping I can use existing plugins/hacks rather than directly hacking the code. All my paragraphs have unique classes so I can search for them and use style.css to display/hide them. So my question is:
What’s the best way to continue to use the user’s filter preference for every subsequent post? Add an additional post argument : &filter=bitmask ?

It would be a bonus if I could filter the database so that only applicable posts were displayed rather than having client-side filtering (using css) to leave empty posts.