In March, there is usually a Shamrock Rally out of Dublin -- this is a fun run, on St. Patrick's Day weekend. Haven't seen an announcement yet, though.
In April, The Snowball Rally and the Targa California -- these are both multi-day events requiring preregistration (now open).
In May, there's Spring Fling, of course, with the PCH Mopar Muscle Tour <https://www.facebook.com/groups/PCHMOPARMUSCLETOUR/>