Starship Troopers is the first Heinlein book I've read, and I'm not sure I'm up for more at this time.
To be honest, Starship Troopers is on one extreme end of the Heinlein spectrum; Stranger in a Strange Land is (over all) on quite the opposite end, and the bulk of his work falls at various points between. Like most writers worthy of any note, he didn't tend to stay still; rather his views (and expression of same) evolved over time. Should you decide to give him another go, you might want to look at one of the following:
Double Star (a very short novel, so not something which would take up a great deal of your time)
The Puppet Masters
Waldo & Magic, Inc.
Time for the Stars (juvenile)
Red Planet (juvenile)
Citizen of the Galaxy (juvenile)
The Past Through Tomorrow (the bulk of his "future history" stories)
I personally would also suggest some of his later works, but these tend to polarize people quite strongly. If you like any of the above, then might be the time to talk about these later works.