Clear your calendar for October 24th (saturday) as AMC is going to run ALIEN, ALIENS, ALIEN 3 and ALIEN: RESURRECTION starting at 2:30pm! That's 10-1/2 hours of pure xenomorph goodness!
Now, I would recommend extending that experience by rewatching either ALIEN or ALIENS after finishing the marathon, to wash away the taste from Alien 3 and Resurrection.
Normally I'd say watch the Special Edition of Alien 3 and the French dub Resurrection, as those versions are much superior to their theatrical release counterparts. But there's something to be said about watching movies on TV "live" opposed to dvd or dvr.
So invite everyone over October 24th and enjoy!