Hibiscus fans, can you help with a selection?

Hi folks,
Gardening in San Jose, California -- USDA Zone 9b, Sunset Zone 16.
Two years ago we had a Hibiscus rosa-sinensis "Brilliant" growing against the northeast wall of our house. We did some remodeling. We put in a new window, so all the plants had to come out. Then I had to grind out an old tree stump, and do some drainage work. It's time to put back the landscaping.
We'd like another H. rosa-sinensis, the same size (the old one was over 6 feet tall and wide) or larger (I might like to , and of equal hardiness. The new hibiscus won't be in exactly the same place as the old one. We're re-planting towards the corner of the house, where it will get a bit more sun -- but I'm confident that the location differs little from the one occupied by the previous plant.
Now, my wife has decided that she would prefer a double, yellow hibiscus to the single, red "Brilliant". (And she is in fact pickier than that -- I've shown her pictures of many double-yellows that she rejects.) I surveyed a few local nurseries for plants. There are seven varieties available locally, none of which are double yellow.
The Sunset Western Garden Book says that there are thousands of named varieties, and I found a nice database of these at <http:// db.lonestarahs.com>. The database is amazing. But I can't determinewhich of these varieties I would be likely to find for sale in the nursery trade.
I would place an order for one with my local nursery, if only I knew what to order!
Any advice is appreciated.
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Brilliant, President, Painted Lady and a few others are very common older varieties. Many of the 1000s are vastly more spectacular, but may not be as durable as these old ones. Many probably won't grow as fast either.
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Wow! I thought no one would ever answer this.
In the mean time, we've found and purchased a "Crown of Bohemia" from a local nursery. I have some contradictory information on this variety, but we decided it was worth trying.
There's no disputing that we can expect double, golden-yellow flowers. So says the Hibiscus database, the plant tag, and the Sunset Western Garden Book.
I have contradictory information on plant size and hardiness. As I noted earlier, we're in USDA Zone 9b, and the plant tag recommends Zone 10. Meanwhile, Sunset tags "Crown of Bohemia" as a "hardy" variety of H. rosa-sinensis, and they claim that the species can be grown as far as Sunset Zone 9 (which is, more or less, USDA Zone 9a). Sunset says "Crown of Bohemia" is "fast to 5 feet tall." The plant tag says to expect 8 to 10 feet tall -- perhaps not quickly?
I may throw a sheet over the plant on frosty nights. It works for our citrus. I didn't do this with our old "Brilliant" hibiscus, and one year we did suffer some frost damage. The plant recovered in the spring, though.
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I doubt if newsgroups are nearly as popular as they were 5 or 10 years ago. I doubt if 1 out of 10 people who use the internet even know about newgroups.
Join the Tropical Hibiscus Mail List if you want active discussion. http://trop-hibiscus.com/ml.html

Most of times I've heard of Crown of Bohemia, it's been from Europeans. I don't honestly know if it's as vigorous as Painted Lady, Brilliant, Albo, President, etc. Those varieties are fairly fast growers so you prune them a couple times a year.

It's not "frost," per se, it's below freezing temperatures. The frost (ice crystals) may offer a little protection. The idea of covering is to trap ground heat -- will that sheet trap much?
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