I'll be at both (though I'll be at Rhymes Farm for RIAT...) Farnborough doesn't give you such a good view but there's always some unusual stuff there (although most of it goes to RIAT aswell) Examples are the A400M which I'll look forward to seeing

...the other option for Farnborough is to go in on a trade day. You get more interesting static and they don't vet you (just go on the site and make some stuff up about your company

)
.mic