Not an expert, although I do have one 20th Century Asian Pear in my own garden, and have planted several in clients' gardens as well. I like the flavor, of good size and juiciness, but does seem to prefer a bit more winter cold than we get here in Berkeley. In a warm winter, it is much later to leaf out, and typically doesn't have as much fruit.

I'd select one on the basis of how much winter chilling you get, and don't plant one that needs more than you get.

One of the the things that complicates locating a specific cultivar is that many have both Asian and English names, so you need to know the synonyms. '20th Century' for example, is also known as 'Nijiseiki.' 'Korean Giant' is also known as 'Dan Bae' and 'Olympic.'
If you're planting two trees you should consider cross-pollination compatibility. You'll get some fruit without cross-pollination, but much more satisfying crops with a good cross. Here's a good link.

Here is a link that might be useful: Raintree's Asian pear pollination chart

Fowler grows the best trees of anywhere, if you're willing to drive (they don't ship). Their trees are hand-harvested on site and have beautiful thick roots. And they are so nice and helpful there. And they're cheap!

http://www.fowlernurseries.com/Backyard.htm

If you want mail order, Bay Laurel has a large selection:

http://www.baylaurelnursery.com/order/clicksite.cgi?cart_id=&xm=on&ftr=AsianPears&p=Asian_Pears

I can't imagine ANYONE having a problem with Asian Pear pollination--usually the problem is TOO many fruits with humungous amounts of thinning required or your branches will break. It is said, and I believe it has happened with mine, that European pears will pollinize Asians, even the vile street Bradford Pears blooming everywhere around here in spring.

Carla in Sac

I've found Hosui to be the most tasty and juicy, but of course, that has a degree of personal preference. I don't grow it, just tasted it, but it should be available from most nurseries that carry Dave Wilson stock.

Here is a link that might be useful: Asian Pears

thanks for the suggestions. Though Korean Giant/Olympic is unavailable in california, all the others are pretty commonplace here. I have finally decided on 20th Century and Hosui (20th c. would pollinate hosui), unless my search comes up on Korean Giant somewhere. The local nursery tells me that there are enough chill hours to set fruit in my location.

Just wanted to update in case anyone else is interested in Korean Giant pear - they are available at Raintree and my tree arrived this week. (funny, all the local nurseries that I called do not carry them).

How many chill hours does the Olympic/Korean Giant pear need? From what I know, I thought it was 500 chill hours. I live in the Sacramento area which gets colder than the Bay Area and I believe we don't get enough chill hours for this pear type. Correct me if I'm wrong, I would love to plant this tree too!

Olympic/Korean Giant does fine in Sacramento area (Yuba City). We planted a tree from Fowler's in 2018 and had lots of fruit in 2019 and 2020. We also bought a Shinko which fruited in 2019 but not 2020. Fowler's is near Lincoln, CA but call first, and maybe they can ship trees these days.