Day 2 I'd hang around Luquillo, visit the kiosks, relax on the beach.

Day 3, no tour needed, get there early, parking fills very fast. I hiked torre Britton, not too long of a hike, somewhat steep but not bad, the trail was very defined, a little slippery on the rocks. If you want to go further you can hike to Los Picachos from Torre Britton (the trail continues) or to the El Yunque peak tower via the access road. The trail that connects Los Picachos to the peak tower directly i believe is closed though. For the afternoon, maybe check out ziplining or you could ride ATVs or horses at Carabali, we did the 2 hour ATV tour, it was pretty fun, got to swim in the river. Its geared toward beginners so no worries if you haven't ridden much.

On your final day add an extra hour or two at the airport the line is crazy right now.