All,
Just got back from Spain. As expected IB would not interline my baggage to US. When I checked in with IB at OVD, they did say if I was going on American (or persumably another One World Alliance member), they could interline the bags. No big deal. Even with claiming and re-checking the luggage, still had plenty of time to burn a few more Euro's in the duty free shops at MAD
--Jon
P.S. Otherwise, IB was very easy to deal with. Baggage was delivered promptly in good shape and even though they don't allow seat selection until the day of the flight for tourist (back of the bus

) class, still got decent seats on fairly full flights.