DL skypesos = worthless. avoid like plague. if you ever tried to redeem international flights using DL, you'll know why.

US Scareways miles okay, but their online, booking engine is weak, and you CANNOT book one-ways, only rt with US miles (a huge huge negative!!!). their phone agents are incompetent too - they thought Austria = Australia. fail.

USAir routes arent really that great outside of shuttle convenience. if you fly to west coast or international, you have to make a connection regardless. hence i recommend United/CO program.