You can have a poster contest where the students illustrate their favorite Dr. Seuss book. Another idea is to have small groups make a collage. To incorporate you can take a survey with your class and have them pick their favorite Dr. Seuss book out of four. Only allow them one vote each and then graph the results and post outside your door.
In addition you can team up with an older class and have them come read with your students or you can team up and read to younger students to celebrate a day of reading!