I'd consider two days a "fly-by intro," preparatory for a much longer visit. On our most recent visits, we dragged along our travel trailer and stayed for two weeks at the campground near Fruita. We're winter visitors only, and it's usual to go all day on the trails and not see another soul.
Some points to consider-
Night, and by extension mornings, can be cold. Dress for it and bring gloves.
The area is vast, with outlying areas requiring long drives around the park to reach. You can waste a lot of precious time behind the wheel trying to "do it all" on a short stay. If you have only a couple of days, I'd concentrate on the areas accessible off the main drive through the park and forget everything else.
Evenings and nights can be magical. If your trip coincides with the full moon, use your days (and a compass) to plan for moonlit landscapes at night.
Over and above all the great geology, the orchards and old buildings around Fruita can be compelling, so don't hesitate to get out for a while after dinner, even if you're not inclined to be out til midnight.
Hike! The scenery from the road is terrific, but perspectives change (and usually improve) as you walk away from the road. Every little side canyon bears investigation, timing dependent on the orientation of the canyon to the position of the sun.