SF->NY flight booked.
NY->London flight booked.
London->Glasgow flight booked.
Glasgow hotel booked. (Finally! It's taken me a few days, but I scored a 4 star hotel in central Glascgow for $75/night. Thanks, Priceline.)
Theater ticket purchased for Glasgow. (Front row center for Rocky Horror show-- WIN!)
Glasgow->London train ticket
Eurostar ticket to Paris and back booked. ($100 round-trip. Ding!)
London->SF ticket booked.
So the only thing left to really worry about is where I'm staying in London, and I'm increasing my Priceline bid by five bucks a day until I get something reasonable. The train ticket from Glasgow to London presents no challenge other than picking a train and booking it.
Other than those items, the only open question is what shows I want to see in London. At first glance, it looks like it's going to be plays rather than musicals.