Yes, I think jmeter is good for that as I tested. It's better to have jmeter and tomcat  on different machines to have more accurate estimates of application load  tolerance

if you have webservice in front you can use SOAPUI, very good tool for webservice testing and loadtesting.

JMeter is good for this effort.

I have a question regarding this issue.
Does JMeter provide enough capabilities for easy stress testing of AJAX web  applications?

JMeter is great for simple sites or plain HTTP load. But if you have a complex
web site probably including authentication, flow and AJAX, I recommend Selenium.

In fact Selenium is not a load  test tool in nature and is mostly used for
functional/unit testing web  sites. But with Selenium RC you can easily detect
hot spots and the use JMeter (or other tools such as curl-loader) to focus and
resolve these spots.

If you need to perform further tuning on tomcat  itself (usually after you finish
up with application  tuning) I may recommend using tomcat native connector
(APR/TC), optimizing connector threading, and a front-end reverse proxy such as
mod_proxy or Perlbal over AJP/HTTP1.1.