I am planning a Eurotrip this xmas and wondering if I can use my Refugee Travel Document to travel from one European country to another. Thanks!

I am planning on flying into Frankfurt and would like to travel to Brussels and Paris. We have 10 days. What is the cheapest way to travel, while still being efficient with time?
I am in law school and my boyfriend is just graduating college. We do not have a ton of money and the train seems really expensive. Any ideas for anything a bit cheaper? Even if it takes a bit longer?