i like the idea of a special minefield deployment zone, for instance, not at the edge of the gravity well, but a bit back, and not all the way back to the planet, sort of like an asteroid belt, that way, your fleet (or scouts or whatever) can jump in safely, but cant advance further without being anihalated. then if and when you do manage to clear a corridor for your fleet, you can move in and do what you are supposed to instead of micro managing mine-sweeping ops until you are practically in the atmosphere.
i mean, look at it realistically, in real life, if you were to put thousands or millions of mines in orbit around your planet, to the extent that they surround your own bases and ships, it would interfere with your own ships moving between trade ports and refineries... so... the logical thing to do would be to put a band of mines at a couple of million kilometers out, and yeah...
so, long story short, i think there should be a special mine laying field not on the outskirts of the GW, but a bit further in, and not extending all the way back to the planet
on a secondary note, i have a small fleet of 5 Kodiaks and 10 scouts to clear out mines, works about 75% of the time, but then again, if they jump straight into a minefield or are attacked by overwhelming force while clearing a space for my fleet to come in, then bam, just lose alot of credits for nothing.
all this said, though, i think mines are a good idea, just had a vasari AI do a very human tactic and move two fleets from two diff planets into one of my systems, if it wasnt for the mines and starbase, i would have lost my planet, and left the rest of my empire open to attack, so... its up to Stardock etc to decide