I'm currently attempting to travel on as many HST diagrams as I possibly can, FGW and if I'm really lucky XC! I prefer to window hang the EXD PLY route from XC because I personally think that the HST sets are nicer - having said that if I do travel FGW, (which is probably 90% of the time,) there is always the chance to pick up window stickers!
I've currently got 16 different location stickers, all of which are different. I've even got most of the named train stickers - I just need to get hold of The Torbay Express and The Golden Hind, I think. One of the guards one a service the other day was particularly helpful, he went back to the guards compartment and brought me back an unused Cheltenham Spa - London Paddington sticker! Seeing as the train had originated from Penzance that morning I'm not quite sure what it was doing there!
I'll have to let you know the next time that I'm planning to do a trip - maybe you might be on the same train!
Just spotted that you're in Plymouth as well! I'm currently sat in one of the student accommodation rooms on Plymouth University campus! Also like you, (it would appear), I am attempting to get as much mileage as possible out of the HSTs!
Also, are you a 50 fan? Because you may or may not know that there's one sitting in a shed on the outskirts of Plymouth that could do with all the help it can get!