Originally Posted by
LAX UA 1K
I suggest you start on the Continental site since it allows you to search all Star Alliance awards.
No, they do not. They show MANY more than UA does but not all. Notably, LH is lacking.
Originally Posted by
LAX UA 1K
You can also book one way with United miles and one way with Continental miles if you do not have enough in one program.
CO does not offer one-way awards at this time. Splitting it AA/UA might work, depending on the account balances. It is also worth noting that CO is adding EWR-CAI service on a 772 in May 2011, adding another *A option with a pretty solid product, albeit only C.
OP, I'd probably go with LH F across the pond and LH C connecting onward from there (no F FRA/MUC-CAI) or LX if you can find the seats. If you are willing to share the starting point and desired travel dates someone here can probably help you find the award inventory you need.
You've mentioned balances in many airlines. How many miles do you have in each of the UA, CO, DL and AA accounts. It will likely make a difference.