When I was a little girl, my granddad told me that coffee and cigarettes would stunt my growth, but for flowers, it's all about the booze.
I read on-line that adding one part alcohol (such as vodka) to 7 parts water keeps paperwhites from getting too big and flopping over. You wait until the plants are 1/2 to an inch high, then switch from regular water to the 7-1 mix. I wasn't paying attention, so mine were about 2 inches high before I introduced them to to the 24/7 cocktail hour. This photo shows my results so far. Because of its depth, I planted the first pot in potting soil, but still watered it with the 7-1 mixture. The bulbs are sitting higher in the pot than the other two, but this pot still got the tallest and will probably start flopping in the next few days, but seems to still be less floppy and tall than in the past when I used just regular water.
The middle dish is moderately successful, but I think the last two achieved the ideal height. Could be because they are more tightly packed than in the large oval dish, as I noticed they have less root growth and drink their vodka juice more slowly. This will be the first time I haven't had to stake the paperwhites, or if I started them in water, just cut them and put them in a vase.
You can use rubbing alcohol as an alternative, but I don't know what the proportions are. One caveat - in the second week, my inner cheapskate came to the surface and I decided to use some rum in the back of a cupboard instead of the expensive imported vodka. What did I learn? Unless you associate Christmas with the smell of a distillery, stick with an odorless choice. When you have a home office, it's already hard enough to explain that even though you can quote Oprah extensively, you really ARE working all day - a house that reeks of rum will not make this any easier.