We do a few things to control the allergy factor for myself and our guests:

1. Bathe the animals regularly
2. Vacume with a hepa filter often, especially the day the guest come over.
3. Brush the cats/dogs before you vacume, it seems to get all the dander and hair away if you brush first.
4. Shampoo carpets often...we are lucky to have access to a carpet cleaner, so this really helps, but may not be an easy option.
5. Wash all linens very often, this will leave less places for hair to settle.
6. Dust often as well, for the reason in #5

We do this stuff and no one we know has had any problems with allergies/asthma at our house. Even me, and Noah and Olivia share my pillow at night.