Hi dr58,
Like yourself, I am an IAD based flyer looking to go to the Maldives. I just skimmed ma91pmh's "getting there" guide, and wow, it's pretty thorough. The interesting thing with his approach is that focusing on specific airlines' route networks and hardware leaves out some of the nuances that might be addressed if he were taking a *program* based approach.
So, I'm going to ramble:
1. You said that UA (Star) miles might be easier to accrue than AA (1 World) miles. As an active participant in both airlines' credit card programs, I'm not entirely sure how true that statement is. If it is true, I'd only give UA just a slight edge. You can pick up something like 90,000 AA miles in one go (well, two cc applications with Citi) whereas with UA you'll have to work a little harder. OTOH, if you're willing to play the Chase Ink Bold small business game, you can accrue 5 miles per dollar spent on all purchases, which really would make UA miles easier to accrue in your case.
2. Somebody already brought this up before, but the Maldives are a long haul from the USA -- going there for just a week seems like a bit of a waste, as you'll spend *a lot* of time in transit. Once you get to MLE, you'll have to take a seaplane to your final destination, and they typically fly only during daylight hours. If you can't time an arriving or departing flight well, you'll force an overnight in MLE.
UA permits a stop-over on a roundtrip ticket. One thing I am considering is a stopover in Japan, or alternatively, Istanbul, at the beginning of the trip. This serves three purposes -- extends my vacation abroad, breaking up the journey a little bit, and help me adjust to the jet lag so I can enjoy the Maldives a bit more. AA doesn't allow this option; its only stopover is at the NA gateway.
3. AA has somewhat rigid routing rules, but there is a small gem in the haystack. AA is quite picky about what regions you are allowed to transit enroute to your final destination. MLE is in the India/Middle East region, and AA won't allow to route via Asia 1/2 to get there. You can only route through Europe or somewhere else in the Middle East. Etihad's connections from JFK and IAD require an overnight layover in AUH in both directions. The good news is that they are timed well enough so that you won't have to overnight in MLE at all to make your sea plane transfer.
The small gem in the AA haystack is that CMB (Columbo, Sri Lanka) is actually in Asia 2, allowing you to route via the Pacific. (You're on your own for you final connection to MLE.) The upshot here is that Asia 2 is a much cheaper redemption than an I/ME redemption -- for example, first class is 180,000 miles rt to the I/ME region, but only 135,000 miles to Asia 2. This is a 45,000 mile difference per person, or 90k for the two of you, which is far from trivial. 360k miles is a lot to accrue from credit cards. OTOH, J can be had for 110k/pax, or 220k for the two of you. That's in the ballpark of what you would get from a pair of AA/Citi card for each of you.
4. As a practical matter, while the guide suggests SQ availability is non existent for partners on the SIN-MLE segment, I think a more accurate statement is that J availability is non-existent, but Y availability is wide-open. So, if you want to use UA miles, expect to fly Y from SIN-MLE.
5. Random musings about alliance developments: Qatar, Malaysian, and Sri Lankan are all joining the one world alliance in the next year or two. This has implications if you want to piece together a more complicated itinerary using the one-world distance based award chart. Routing over the pacific, it's more expensive than a straight round trip.
To close this out, I don't think there's a clear-cut best option for someone with "limited" amounts of miles. AA offers the most straightforward routings, but the most expensive. AA also offers the cheapest routings (terminating in Asia 2) at the expense of a cash ticket (or other mileage option) from CMB-MLE. UA offers a stopover, which is very appealing, but highly likely going to dump you in coach from the 4 hour SIN-MLE segment.