I've determined from personal experience that the lack of availability of 'O' tickets is partially a myth. A large number of seats are held for high rollers and VIP's until 1 - 3 weeks before the show. After that, significant availability can open up.

The website is the worst way to order tickets. It often does not display the best seats in each price range. For example, wet seats in the first few rows will generally show up even if center upper orchestra seats are available.

Usually the best ways to check availability and to directly purchase tickets:
First choice: In person
Second: By phone
Third: Website
(Other ways such as eBay/brokers/scalpers may fit in somewhere, too, of course.)

Yesterday, I bought two seats in the rear center of upper orchestra for this weekend. And if better seats open up before the day of the show, it's possible to exchange up to the better seats for no charge.

Some ticket staff members have recommended calling on the Sunday or Monday before the day you want tickets.

I've found this same strategy to apply to the other Cirque shows. Last night, I saw that Zumanity showed second row center seats for this weekend. One week ago, the best seats online were in the balcony or on the side. (I really wonder how long Zumanity will last. It always seems to have so much availability, but it has lasted much longer than I thought it would.)

Also of note in yesterday's news: "Wynn pays $16 million for rights to revamp 'Le Reve'"

"Dragone company spokeswoman Ingrid Jensen says Wynn intends to add lights, a laser show and perhaps more performers to the aquatic performance 'Le Reve.'"
...
"Jensen says Wynn has hired the artistic director of surrealist dance troupe company MOMIX, Moses Pendleton, to complete the expansion of the show by some time in 2007."