In a long term scenario I'd recommend using technologies backed by a Sun specification. This has so far proven to give multiple implementations resulting in choice (frequently also open source implementations), plus behaviour tends to be very well defined.
That will help you in a maintainance scenario, which - hopefully - your code will end up too in time. Well-written code lives forever :)
In this particular scenario I would suggest JSF. I have only tried the Apache implementation of 1.1, but it hurt to be on top of JSP. We are to revise it soon - I expect to look into having JSF on facelets.
