I've been fortunate enough to have a moderately crash free game, only had two or three CTD's in the open world but the Ratways in Riften has given me about five or six crashes now.

I'm not expecting a fix but I was curious to find out if it's just me.

I'm also trying to do that quest but keep crashing all the time outside of Riften. Two times I crashed right before killing the dragon, and once while trying to find a way into the city while the guards were busy fighting it. Very annoying. I can't play like this.

Yeah, sounds pretty much the same as me, 90% of the crashes I've had are in or around Riften, specifically though, the Ratways give me a mostly repeatable crash.

You can get in, in the very least. I crash outside 100% of the time.

You're not alone. Last time it was winterfell. half an hour ago it was riften. 5 Crashes. I gave it up.

I haven't had any problems in Riften that I haven't had in other places.

Try running Skyrim from the executable file, rather than using the launcher. See if that helps at all.