Fortunately the sun has at least a few billion years worth of hydrogen left before it starts its full on helium burn and it’s expansion to red giant phase. Current estimate is 500 million years it have increased luminosity but not size enough to make Earth no longer habitable. Given that long of a timeframe even closer in Venus will have hundreds of millions of years before the 50km cloud deck heats up to temps too high for humans to tolerate in a sphere floating. Venus has enough atmosphere to shield from a solar flares type event plus your water tanks make fine shields 3 feet of water can stop any gigavolt level cosmic rays or solar wind at its theoretical worst.
Mars thin atmosphere doesn’t offer the same amount of protection you would need to be underground or under a water pool in any big solar event. But Mars has water in big amounts ,nitrogen at 2.5% and plenty of CO2 for carbon and oxygen. We know there is phosphate minerals present too sulfur should be there as gypsum salts its what gets left behind when salt water evaporates or sublimes.
Jupiter is a charged particle nightmare environment. Humans would not survive on the surface of Europa or any of the inner ice moons of that system.
Titan is cold very cold but humans could stand on it in cryosuits it has 1.5 bar of pressure so no pressure suit needed just protection against liquid methane temps and oxygen. It would be dark cold and slushy humans would struggle to have a habitat there such little solar insolation means things won’t grow even if you had a warm dome you would need LEDs there is no free oxygen and only trace CO2 so you would need to drill deep into the crust to hit a water ice layer and mines H2O that way for the O2 and the water. At minus 290F even the best insulated dome is going to take a nuke of some large size to keep it warm and then it will be sinking as it melted the solid methane and ethane ice of the surface I guess you could float it on a liquid methane lake and let it boil off under you hoping the lake volume is enough to.keep up with the boil off rate vs condensation and return rate.
Mars is the best spot for humans in domes and if we can get a plasma bubble in front of it then crashing some meteors into the polar ice caps could throw up a decent atmosphere after some big hits and the debris settled out. Deorbiting one of the Martian moons and crashing it could also up the gas content by impact heating and outgassing of the rejected debris. Needless to say you don’t want to be on Mars when you start playing cosmic pin ball. Seems easier to build large mega domes and use TBM machines like the boring company already does to drill out miles and miles of subsurface space. Easy to pressurize, plenty of radiation shielding, you get access to all the water bearings strata you are boring through plus the heat of your tunnels melts more surrounding them drain that off via French drains and use it.
Some good news about our future Mars missions:
Blue Horizons has the Mars Telecommunication Orbiter in the works - the launch engine will use a combination of chemical fuel and electrical. This will allow a wide latitude of possible launch dates since in will have potentially unlimited power.
The MTO itself will be a series of satellites with Lan/Wan abilities allowing for signals to be relayed in near real time. No more waiting minutes for a reply.