I like crim pro, so I would probably do Katz (not ok for govt to use electronic equipment to listen in on a dude's convo in a phonebooth without warrant), Kyllo (not ok for government to use a thermal imager without warrant to see if dude is growing pot in his garage), Jacobsen (entrapment and kiddie porn).
Another case that you could easily argue both sides of is Bd. of Educ. of Indep. School Dist. No. 92 v. Earls, which says that it is ok for schools to drug test kids in extracurricular activities.
You might like Kyllo because it is all about how to balance the preservation of 4th Amendment rights with rapidly advancing technology. Be sure to read Stevens' dissent.