You can credit them to any Star Alliance member. United could be a good airline for the Carribean trip you mention. Perhaps another *A airline would be good for travel to India. For economy award flights in *A, United is tough to beat. But if you don't want United miles and you fly American with any regularity, you could credit to US which will eventually become American. That's more of a medium-term play and we don't know how long you will be able to credit United flights to US. Aegean is a popular option due to their easy status levels. Your flights would get you to Gold if they credit at 100% (depends on fare class). That's 3 years of Star Alliance Gold. You'd get enough even if they only credit at 50% but you're sacrificing half your miles then .