Well, I did book my trip ... on AA.
The RN availability on UA was ridiculously low during my travel window: ZERO to be more precise. I tried all possible permutations between all gateways on the US side (IAH, DEN, ORD, IAD, EWR, JFK) and the the four airports that are connected to Bruxelles directly by train (AMS, CDG, FRA, BRU). Nothing. Absolutely nothing.
Decent discount BF fares around $2,500 were available on UA, but they required 10 day minimum stay, or (in the case of still tolerable fares around $3,500), a Sunday stay. I could not meet these requirements so the only fares available for my travel dates were about $5K to $6K.
I then went to EF and within five minutes I found availability on AA from DFW to FRA, returning CDG-DFW. I hate to not be loyal to UA, but in this case I had no choice.
Apart from the inconvenience that I have to fly out of DFW on AA, I am most concerned with what appears to be a disturbing trend here -- all RN availability appears to be zeroed out on international flights.
Can anyone explain the wisdom of this new UA strategy of not releasing R inventory?