After Mars, what would a manned Starship mission to the next planet look like? What is the next easiest planet to reach? Venus or Jupiter?

Would a fully fueled Starship be enough for the round trip? Or, would there be an extra module or segment (probably expendable)? Two Starships piggybacking or linked in some way?

I'm imagining just going out for a few orbits, to observe, not land. How long would that trip take? Maybe in 20 years there will be a DearVenus or DearJupiter.