I took Intro. to Logic & Critical Thinking (which sound like the equivalents of your courses). I believe that Logic was more relevant to the LSAT, altough everything I learned in Critical Thinking was covered, to some extent, in Logic. If you're able to I would recommend taking both, but if not Logic would be your best bet. The problems solved in a reasining/thinking course are not as applicable to the logic games. Logic will help you to hone the basic skills that allow you to increase your speed in the Games. I wish I could've taken these courses closer to the test date b/c they'd have help (I took both over 2 years before the LSAT).
At my school, the course was just listed as "logic" or "elementary logic." But if you read the course description, it would mention symbolic logic in the description. So look for that. The course will probably be offered in the Philosophy department.
At my university, they also offer a course entitled "Practical Reasoning," which is also a logic course, but it's different from the symbolic logic - sort of prior to symbolic logic logic - they only do a little of symbolic logic towards the end. However, in that course there's a lot of problem solving, very much like the ones on the logic part of the LSAT. I never took that course, but people who have, told me that it was extremely helpful in preparing for the LSAT. So keep an eye out for something like that at your school too.