Well, to be honest, my Shuttle kit has been waiting for more things to be done to it for 2 years now. It's always at the back of my mind though, because I just love that machine and do want to have the kit in my collection someday. I too have the Monogram kit, and yes there is some work needed to get a good replica. I read that mixing both the Revell and Monogram kit parts helps, but haven't yet decided to go that way. In fact, what I want is to detail the cargo bay and I find it really hard to get enough reference about any particular mission that interests me. Always a view missing, or else! The tiles are a big problem for a kit that size. I had read that tiny bits of tape could do a good job in replicating the whole effect. But just thinking of the number of tiles to add to this monster of a kit makes me ill... So far, the only shuttle I've ever completed is the Hasegawa Egg-Shuttle (the caricature kit, back in the 80s), to which I added 'egg' shaped boosters and ET, the whole thing displayed on a plate. It was fun and cute. I've also had the idea of doing the Hasegawa kit in 1/200. It is rather nice, and would not require as many details as THE BIG ONE...
Other than this dream model, I'm busy with lots of small scale AFVs, an Il-76, a Macchi MC-202, a 727-100, a Junkers G38, and a Caudron racer, but who knows when any of those planes will actually be completed!
Keep in touch. I really want to see how you're getting on with this Shuttle!