Misty, you mention the two ends of the spectrum in your examples. My experience with Siebel was that it was an inflexible, difficult to get into tool which was (at the time) superb at managing huge amounts of information over cross-function groups globally.
The "lower-end" is occupied by tools such as Maximizer, ACT, and Goldmine. These are superb for SMB use and cover all of the subjects which you've portrayed. In fact, we pushed ACT to the limit and were sync'ing every Friday via FTP (5 users spread across the city of Toronto). You need to back-up fastidiously to some device which is separate from your computer. It works well with MS Outlook (you don't mention your set-up).
You don't mention how your office is configured for technology. If you're not "on the lead edge", you might want to consider something like Salesforce.com. The beauty of this tool is that they are responsible for all of the infrastructure ... you just connect via the web! It is middle of the road in terms of cost.
After your research, I think you're going to end-up with ACT ...
Good luck & Good selling!
Pat