Another Starship possibility I haven't mentioned (not my idea). I first heard of it on the
Angry Astronaut channel of YouTube. Though he doesn't make all the points I do below.
Scaling Starship DOWN. Use fewer segments to make a shorter orbital unit. Lets say 1/3 length with (assuming capacity scales with length) a 50 ton capacity.
Why?
Reducing the length that much reduces the fuel capacity from 1200 tons to 400. Refueling in orbit takes fewer trips by a full size refueling Starship yet leaves the mini Ship the same deltaV capacity (Fewer Raptors too). Should be able to act as a mini Lunar Ship as well as a Mars capable lander.
Reduce the Super Heavy Booster the same way results in a Heavy Booster. Mini Ship with Heavy Booster =
Fully reusable Falcon 9 replacement. Another option would be to use a Super Heavy but take it higher before separating leaving more delta V based on the onboard fuel of mini Ship. It would be more than double the capacity of Falcon 9 and 75% of Falcon Heavy so it replaces both for smaller flights and likely reduces costs. The only real issue is shipping them by road due to increased diameter is much more difficult.
Maintenance costs should be cheaper than Falcon 9 as again they use the same components as the full sized Starship AND the same technicians. 1 facility services and 1 builds BOTH Starship and Mini Ship. The Falcon facilities could either be shut down or used to service the hopefully higher volume Starship and Mini Ship launches.
This results in a smaller cheaper lunar lander and Mars lander for early missions with a minimized development cost as it uses all units that are first developed for and proven with Starship. Cheaper for support than Falcon 9 as (almost) all components are in use first for Starship.
Fewer engines for Heavy Booster means it is quieter so might be launched from locations Super Heavy would be too noisy.