Hi Bill,
Given your requirements and time constraints, I suggest you take a look at Visual ProMatrix. They have documentation and a free trial version online. ProMatrix provides a highly productive development environment and excellent support for applications that need access to both local data and a SQL back end. Also, take a look at xCase/xCase2VPM to speed up your development time.
If n-Tier and web development are important to this project, then you might want to look elsewhere. ProMatrix is hard at work on these features, but not there yet.
I haven't used other frameworks, so it is hard to give a completely objective comparison, but it seems that the learning curve with ProMatrix will be shorter than with other frameworks. You'll get excellent support on the newsgroups. That is also true of most other frameworks, so regardless of your choice, you won't end up on your own.
Have fun!