Can you go directly from SL to Mavericks?

Why not? It's going to be distributed through App Store and SL has the App store.

 

I don't see why not as long as your Mac meets or exceeds the minimum required machine specs. You should know that the Mavericks GM isn't out yet, it's only a Developer Preview which is unfinished and unless you're a Developer making apps for the Mac it's best for you to wait until the retail version hits the streets. Also unless you're a Developer you won't receive the software updates in the DP version nor will you receive the GM...unless.

 

Yes, you can. The only problem is if you are running a lot of software that won't run on Lion or Mountain Lion. The upgrade goes well, it's just the third party apps that threw fits in my case.

After that experience I decided to create a thumb drive installer for Mavericks and did a clean install.