Install a light lift if your fixture has many bulbs or crystal beads that require frequent cleaning. Light lifts are available in both mechanical and electronic styles; both will raise and lower the fixture so that a person standing in the foyer can change bulbs and clean the fixture from the floor.
Extend your reach with an extension pole designed to unscrew light bulbs from beneath. These poles only work for fixtures whose bulbs point down, of course. The flexible "hand" part of the pole grips the bulb with gentle pressure, which allows you to unscrew and replace bulbs without climbing. This solution does not solve any cleaning issues -- an extension duster may help in some cases, but they can be clumsy to operate and may damage delicate surfaces.
Acquire an extension ladder with projecting arms used to hold the ladder away from the wall. To see how these ladders work, hire a professional to clean both the fixture and any upper windows, and watch as he sets the ladder up, secures it to the walls and moves it in and out of the foyer. Specialty fitted ladders can be dangerous to use without proper training.
Rent scaffolding and have it assembled in your foyer. The scaffold should be high enough to allow you to easily reach the fixture.
Use a rod with a hook on the end if your fixture has a chain and if you have a second-story landing close to the chandelier or fixture. In some cases you can use a hook to push or pull the fixture over to the railing so that a second person can quickly change bulbs and dust the fixture. Move slowly so you don't break crystals or glass elements, and do not allow anyone to be in the foyer below during the process.