The course includes: Regular Languages, Context-Free Languages, Turing Machines, Decidability, Reductions, etc. Do you know of any collection of problems/solutions suitable for a senior course?
I agree that Introduction to the Theory of Computation by Sipser is good text, but I also recommend taking a look at the Stanford CS103 course page archive, which has a lot of great supplementary resources, including handouts, problem sets, and lecture notes.
The standard text is probably the Sipser book. It's fantastic, and the problem sets are quite intellectually rich.