Answer: At last count there were over 5000 cultivars so unless you have a huge garden, you'll just have to choose your favorites! Here are a few reference books (check Amazon.com or your favorite book store).
The Genus Hosta: Giboshi Zoku
The Hosta Book
The Gardener's Guide to Growing Hostas
This is Gardening: Hostas
The Hosta Handbook
Hostas (Foliage Plants in Garden Design)
by Sandra Bond
There's also an American Hosta Society (www.hosta.org) with tons of information on their website.
Best wishes with your hostas!
Q&A Library Searching Tips