Mars is doable. Luna is convenient. Venus is pure acid under ridiculous pressure that melts any probe in minutes. Europa is too far for anything serious. Enceladus is even further away.
It's an interesting concept to be sure, but is it technically feasible to make it reliable enough? The transition from orbital velocity, to atmospheric entry and blimp deployment sounds like it would involve significant stresses, and that's after being in space for half a year to even get there. One small micrometeorite and you have a leaky envelope and the mission is over.
I think there was a proposal for a solar powered winged probe which although less cool, would be probably more likely to succeed.
Some of the earlier Mars rovers used inflatable balloons to cushion the landing. They bounced around for dozens of meters on rocks without popping. Not an expert by any means, but would think it should be possible to inflate a gas bag at a certain altitude, after dumping the thermal shield and using a parachute to slow down.
A powered-flight probe would be interesting in that it could be more easily directed to specific areas and have the ability to stay over a given area. A balloon would likely not be as controllable.
But would be happy with any Venus mission, even a low altitude orbiter would be cool.
For sure, Venus needs exploration. I'd like to see an orbiting station with a 10 year mission to explore the Venusian atmosphere via drones or other methods.
