The free walking tours are excellent, you must tip the guide that is there only income and they are fantastic at their job. You can find them on facebook they have a page. Ruin bars are great to see you will probably go at the end of a tour. Budapest is an amazing city. Definitely go to one of the baths they are all over the city. Great restaurants fabulous architecture. about 5 years ago
Definitely agree on the free walking tours. We did them in every major city in Europe.
We also rented bikes and went to Lukas baths and enjoyed a stroll through Margitsziget Park on the way where we enjoyed the largest cotton candy we've ever seen (https://www.facebook.com/photo.php?fbid=436875306334959&set=a.338587989497025.76318.327706030585221&type=1&theater) about 5 years ago