Sweet spots are redemptions that come in at the upper limit of a distance band, making them good value redemptions for that particular band, in terms of distance flown / Asia Mile.
In the case of Asia Miles, the band limits are 2,750, 5,000 and 7,500 miles. There isn't a large difference between the Asia miles costs for the 7,500 and 7,500+ mile bands, hence we'll focus mainly on the 2,750 and 5,000 mile bands.
As always, redemptions should be made for business-class and above, as the various fees and surcharges generally make economy class redemptions poor value for money.
1-way redemptions are particularly good value, as these tend to be exorbitantly expensive.
1.) Penang - Hong Kong - Jeju / 2,575 miles / 10,000 Asia Miles + RM283 each way on Cathay Dragon economy-class
Ok I know I said it's not worth it to redeem miles on economy-class flights, but this is actually not a bad deal. It's a single stop flight to Jeju (for all you Winter Sonata fans) and it normally costs RM2,700.
The downside is that you need to stay overnight in HKIA on the return leg, which will cost an extra RM250 on a twin share basis. Adding this RM250 to the RM566 in fees means that you're getting RM2,700 - RM816 = RM1,884 in value from the 20,000 Asia Miles, or over 9 cents per mile, a very decent amount.
2.) Colombo - Doha - Milan / 4,952 miles / 50,000 Asia Miles + ~RM500 each way on Qatar Airways business-class
This flight is really at the upper end of the distance band! You'll have to make your way to Colombo but both MAS and Malindo fly there for very reasonable rates. The payoff is a stopover in Sri Lanka and nearly 12 hours in Qatar Airways business class to Milan.
You can also route to Zurich, Rome, Munich, Vienna or Prague for roughly the same costs. Cities further west like London or Paris are out because the distance would exceed 5,000 miles.
If you prefer not to stop over in Sri Lanka, Penang (or KL) to anywhere in Europe via Doha will cost 70,000 miles each way.
3.) Penang - Doha - Amman / 4,515 miles / 55,700 Asia Miles + ~RM500 each way on Qatar Airways business-class.
Jordan is usually a very expensive place to get to, but that's irrelevant when you're paying with miles! This is a great route, as you get to fly direct from Penang to Doha on Qatar Airways before connecting to Amman.
Interestingly enough, Qatar sells certain regional business-class routes as first class. The seat is the same but you get access to the exclusive Al-Safwa lounge. DOH-AMM is one of these routes so you'll get access to this amazing looking lounge.
4.) Australia - Hong Kong - America / 7,500+ miles / 85,000 Asia Miles + RM??? each way on Cathay Pacific business-class.
This is probably the best value redemption available, but you will need a whopping 170,000 Asia Miles for a return trip. However, you'll be able to fly from anywhere in Australia to anywhere in North America, all on Cathay's longhaul business class.