I've spoken with some other people in the field and they've also steered me towards Tomcat, for no other reason that it's a cheaper alternative to Weblogic, Websphere, etc... They also suggested starting off with Tomcat and see if that works, and if not, work your way up. The only problem with this process is that we don't want to learn in production that it doesn't work, but rather in a test environment. Thankfully we have some programs that can simulate thousands of hits per second, so that might help us determine the best app server in our test environment.

Thanks for the feedback!