firstly it blows you up at about 200 km, and planet models CAN be pretty useful. Imagine launching from a station in the planet's orbit... or even the planet itself
(although you'd start some kilometres off the surface, certainly)
Real planets are really useful, as long as you're still able to use the 2D backdrop ones.
That glow point idea... well, i dunno if it will work, but i think you'd have to have a 4096x4096 texture to have it look good, and that would slow down most people again
Maybe you could add a Planetary fog that creates an atmosphere effect when you near the planet too close.
I'm thinking of something pretty simple, like blending a screen sized ANI over the display and adding the atmosphere hue to it. But it'd be sooo cool