First, welcome to FT, neighbor.

Your route is doable for the most part - a couple of glitches in your plan (for example, there's no Oneworld member that flies SFO-SEA; AA codeshares on Alaska are ineligible, drat.) But no big deal.

Do you have any mileage plan addictions? RTWs are excellent mileage-earning devices (in business/first more than coach, but still decent) for those who want to adopt the mania. If so, then you'd need to pick a frequent flyer plan, and that might have an impact on your route (e.g. no American Airlines miles on BA flights between the US and UK, such as SEA-LHR.) So that could also influence your decision.

An LONE4 bought in the UK (today) is around $1400 less than if bought in the USA. If the dollar continues to weaken, that gap is likely to narrow, since RTWs are priced in local currency. So the first question is, can you get to the UK and back for under $1400? Not so easy a question, since round trip fares spread out over the better part of a year are typically much more expensive than those with shorter turn-arounds. Two one-ways might gobble up that $1400 without heavy breathing, so the advantage is negated.

Same goes for business class tickets, with the differential slightly more dramatic. In the case of DONExs, the UK is not a cheap place at all; Sweden in Europe is more favorable, and Japan in the other direction, but for a RTW hitting Oz and Africa, you'd be adding a 5th continent to start in Japan.

One big difference in business class v. coach RTWs is the mileage earning gap. In a modest LONE4, you can earn maybe 25-40,000 miles in the AA program. With class and elite bonuses (easier to score using business class) it's not hard to double that total or more with the same route on a DONE4.

And therein lies one of the selling points for D over L. Your $3K extra (let's say) for a well-constructed DONE4 will earn both you and your wife enough miles to take another big trip - possibly another RTW - in business class later, or a couple of nice first-class domestic trips, etc. If the award trips have an aggregate street value of say $5000, then the extra you'd pay for the business class RTW in the first place is worth it if you have an interest in further travel. Of course, a nice side benefit is that you'd travel around the world comfortably the first time, rather than scrunched in the back of a big bus.

Take Africa. Really, really expensive place to get to from North America, especially the west coast. Europe? Not so hard. Solution? Bank a ton of miles with a DONE4, then spend them later on AA's most excellent 75,000 mile business partner award from Europe to Africa. Earn miles flying to Europe, then burn them flying to Africa. Rinse, repeat.

I don't know if this answers any questions. Your itinerary is quite minimal given the power of the Oneworld Explorer - for example you're allowed 6 segments in N. America, so throw in a trip to the Caribbean or Alaska along with OMA.. easy. Or see more of Australia or NZ while you're in the neighborhood. 20 segments is a lot.

Anyway, hope this helps - come back for more any time.