Got STS-1, 8 and 41C completed...
didn't get the STS-8 Badge because I started in orbit (I lated did the T-01:50:00 - but I only got it into orbit (so no badge - donno if it counts or not)
can I suggest STS-32 as a new mission?
retrieving the LDEF sound like a challenge - due to it's enormous size, getting it in the Payload bay should be a "little" tricky, and it has a very low pregee alt, because it was only two months from re-entry when recovered (plus the model already exists, which would make this mission...