This is a good topic, and quite a few great suggestions already.
I'm also a bit new to the points world. I'd say that once the flights are set up via Delta, you can see the partner links at the bottom of the confirmation page. As noted above, some of these partners are a bit meh. Hertz is hardly a go-to, but Enterprise/National have been reasonable. From a hotel standpoint, as suggested, be a free-agent.
My big suggestion for the cars is a bit off the reservation at the moment: Silvercar! I love 'em, and I love knowing what my cost will be at the outset...no hidden fees, taxes, high spec vehicles/content yada yada.
Maybe give yourself the first 4-6 trips for evaluation, then set your strategy for maximizing redeemable points, in whatever form they come at you!