I arrived in in Thailand last spring one month before I planned to. I went from Tourist Visa -> Non-Imm "O" for retirement -> 1 year extension. My extension expires in mid Sept. 2011, I want to change that sometime between mid October 2011 and end of March 2012.

I see several ways to deal with this.

Attempt renewal 6-7 months before extension expires. Requires immigration to bend the rules, so I expect to pay an informal fee, perhaps a substantial one. Pros: may be minimal hassle. Cons: may be high fee or impossible.

Let extension expire (or leave without a re-entry permit) then start over next year, entering Thailand with a Tourist or Non-Imm "O" visa. Pros: I know how to do this, Cons: Unless I can get the visa in Central or South American (or possibly Houston, TX), I have to do additional travel to get a visa.

I will be in the states for a few weeks, so I could get an O-A visa if I leave without a re-entry permit. Pros: It's an O-A visa, Cons: Don't want the documentation hassle or the cost of hanging out in the states while getting it.

Leave the country now without a re-entry permit, return in a few days with a tourist or non-imm "O" visa and start over. Pros: It's by the book. Cons: The immigration people will think I'm an idiot. Don't want to transfer the required dollars to baht at current rates.

Just live with it.

Are there other options, or errors in what I think are my options?

You summed it up, but I would not recommend bribing immigration. If there is enough reason, they might extend it early, but you want it very early.

Best is to try to get a new non-O visa, which you can also get in South America or in neighbouring countries, such as laos or malaysia. it can depend on the location where you apply, but you can expect to be asked to show proof of income or money in the bank (doesn't have to be in Thailand).