I immediately check the Celestia Motherlode.
The reason being that you can almost get a sense of how big something really is with it since it displays your distance to it in au (or ly, Kpc, Mpc).
I encourage you to try it, hit H then G to go to sol, then scroll away first to 1 au, then 10, etc. The sun is still quite bright at 1 ly.
Imagine how big that thing appears at 1 ly distance!