Thank you both so much. Considering the deal I got on the tickets, under $500 for the two RT with fees, I may just do that... my grandmother graciously gifted us some Hilton points too so we are having a luxury honeymoon at a deal.
My type A personality is wishing there were some way to book the ENVOY now for my Oct. flight... guess there's no secrets for that?
Anyone have experience/thoughts on the likelihood that I'll be able to do it for Charlotte, NC to gatwick in early october? (ahh, and just realized that's one way of course...

) hmm, not sure 2000 is worth it. would appreciate any thoughts on how much better the upgrade makes the trip...