Hi Sara. Since it's Task/Timeline information (vs Custom Data changes) that you're wanting to audit over time, I think that you're on the right track using Baselines. If (for example) you took a baseline every Friday of every Current project (and set that latest baseline to "default"...that part is important), you could then do a couple of interesting things.
First, when looking at a Project using the Legacy Gantt View, you could can turn baselines "on" to visually compare the baselines against the planned and (optionally) projected dates to see the slip; and "toggle" between different baselines by selecting them from the drop down, essentially scrolling back in time.
Second, you can create a report on Baseline Tasks to show similar information in a grid format on a report for whatever filter or prompt you wish (e.g. certain tasks, certain projects, etc.) so you can more easily focus and quantify the variances. By design, the report uses (only) the Basline Tasks on the Baseline that is (currently) marked using the "default" Baseline setting I mentioned.
Once you've tried these approaches to confirm that they're of value, you could also consider automating the baselines using our Create Baselines , which you can run ad-hoc (e.g "create a basline for ALL my current projects"), or scheduled (e.g. same idea, but "Friday at noon").
Regards,
Doug