A hollow discus-shaped object in low Earth orbit around forty kilometres across, filled with air at one bar and covered in photovoltaic cells. Their energy is beamed by microwave to a central "sun" consisting of a large sphere with a glowing surface, made of white LEDs or some other fairly cool electrical
Around this central sun, a number of hollow spheres of magnetised steel mesh are steered in "orbits". They are of the order of fifty metres in size, and rotate and travel round the sun by means of jet propulsion, taking the same time to go round as the planets in the solar system. They are surfaced in various ways, and are generally retro in style.
Mercury: This is around fifteen metres across and orbits about two hundred metres from the centre. It's covered in concrete and has artificial moulded craters. The same face is kept pointing to the sun by jets. The sun side is heated to above boiling point and the dark side refrigerated to below freezing.
Venus: Roughly twice the diameter of Mercury and twice the distance from the sun. Heated to tropical temperatures internally, with a waterproof lining above the mesh. An aquarium-style ocean stocked with tropical fish and the like covers the whole planet, with a few "islands" on stilts dotted here and there, planted with lush, jungly-looking houseplants like Sanseviera and Ficus. Animatronic reptilian monsters stalk the land. The water will tend to stay around the planet due to cohesion and its tendency to form a sphere. Food plants are grown here.
Earth: About fifty metres across and half a kilometre from the sun, this is like Venus but cooler. It has frozen poles and a heated equator, with land mimicking the continents on the real Earth but covered in small, futuristic-looking buildings. You can get around by jetpack if you want. It has a proportionately sized Moon with a domed moonbase on it.
Mars: Half the size of Earth, around a mile from the sun, covered in iron-rich magnetic sand and canals, which are enclosed due to lack of gravity. There are also "ancient" ruins scattered about on the surface and robot aliens roam about.
Asteroid belt: A proper one, not like the real one, with motorised rocks strewn liberally in a ring centred on the sun.
Jupiter: A glass sphere about half a kilometre wide, with coloured liquids convecting around inside it. No ring. Small Galilean satellites like the inner planets but ice-covered.
Saturn: A painted, smaller sphere with a solid ring placed around it, probably with Titan.
Uranus and Neptune: Smaller, simple coloured spheres.
Pluto: A ball of solid iron about ten metres across.
The inside edge of the whole discus is painted black and studded with lights to simulate constellations.
People travel around the environment noisily in funky-looking finned spaceships, dressed like Buck Rogers, Dan Dare or wearing "space suits", all suitably naff, firing ray guns at each other. Some of them dress up as the likes of little green men, treems or tentacled beasts from beyond the sky. These get the chance to travel in flying saucers. Everyone wears magnetic boots to simulate gravity on the "planets". There should probably be some Robbie-style robots too. The whole place is used for role-playing, making movies or as a resort.
Would Virgin Intergalactic be interested?