would also like to add for great effects and just pretty...when ever I visit a planet and I can fly through the rings and it ripples or leaves a trail in my wake, I find that enjoyable as well, usually fly around a couple times :p
Today, I went to Cardassia System. While I was fighting (??? Forget who) I saw that there was the Spread of the Galaxy Core that I mentioned in the OP, But, it was on the east side of the map instead of the West side.
It made me think I had actually Flown Across the Galaxy to the other side of it. In the OP, it was on the West side of the map. The reversal of position was COOL!!
Found another one which must be my favorite ground map yet.
Can remember where it was, explore such and such nebula but there was a mission where you had to beam down and scan objects in this case turns out ancient Klingon graves.
But the setting was stunning - a sort of glade with steep hills on all sides with trees all the way to the top and this difused lighting was quite incredible. Wish I had taken a screenshot had enough time there lol.