My brother and I have played a couple of super-large X-Wing games, and I thought I'd share some insight from them and see what other's experiences are with huge battles. As a side note we stared with 1,000 point per side, and that was just a bit too much to squeeze in in an afternoon. So we scaled it back to 600 point per side: "Double Epic."
The play area is 6x6. Luckily for me, I have an old table I made for when we used to play fantasy miniatures battles; I made it 6x6 because 3' was a comfortable length to reach stuff in the middle of the table. So, blind luck that Epic is 3x6, so double Epic is 6x6. We deploy out to range 3, and typically only have 1 round of only movement before engagements begin on round 2 (so it's not really too far apart).
We have made the Huge ships a requirement. You can have up to 6 Epic points on table, but you must have 3 Epic points. The last game, my brother fielded 2 CR-90's (very cool to see 2 capital ships cruise across the board in formation), while I fielded one Raider and 2 Gozanti (more spread out in a pincer formation). So, we each had 4 Epic points in play. Which still leaves plenty of points for a starfighter screen.
The last 2 games we have played with 24 asteroids. It has seemed to crowded both times, so I think that 12-18 obstacles in probably plenty.
The game lasted about 5 hours of play time, plus about 1 hour set up and 40 minutes break down. We typically do not "finish" (all ships killed), but one player will concede (which in truth, feels more realistic. . .how many commanders are insane enough to let all of his forces be slaughtered?).
Edited by Darth Meanie