Given that the received wisdom is that redemption value is marginal on European flights, what would be alternative destinations for a long weekend (but not too long - don't want to use all the baby-sitting credits up with Grandma...) assuming that we'd have to go via Heathrow.
Basically, I want to go somewhere impressive (where I can get some benefit from using my Amex voucher and going Club) but where I don't lose the best part of two days in transit.
I'd reccomend Nairobi. Good flight times, excellent all year round redemption availability, coupled with a huge amount of things to do when you get there.
India is also good for availability but does have the problem of requiring a visa.
Carribean is good, but availability can be tricky.
If you're feeling adventurous, Sao Paulo has fantastic availability at weekends with Iberia.