My local shop is holding a starwars sat and me and a friend are demoing xwing. We have both cores avilible. What kind of lists yould you guys recomend for demo using 1 of either core

Use the supplied missions.

I'd run the one X-Wing versus two TIE Fighters intro game exactly as described in the Learn to Play books that come with the core sets. Since you have one of each core, you could even have two such games running side-by-side. This will keep it quick and easy. If you then have a player or players who are interested in a more extended match, set them up with the recommended point values from the Core rulebooks (I think it's something like 31 or 35 points, depending on which set you have?).

Luke with R2 vs two Tie Academy pilots and let the newcomer be Luke.

The game will last long enough to show the rules then let the next interested player in line rotate in.

If you're demoing larger games I'd say do 50 points and have there be partners to get the full 100.

The perfect beginner 50 point build is the Millennium Falcon piloted by Chewie, Luke as crew and the title. Tell the player to always focus or dodge and dodge be the default if they don't know what to do.

My reasons for saying that build is so good for beginners is that's its an Iconic ship, it has a turret (no out of arc shots), Luke allows a reroll (hitting is fun). and Chewie means you don't have to bother with critical hits.

Here's a little write up I did for the blog "The Metal Bikini" http://www.themetalbikini.com/2014/05/hosting-demo-game-by-cliff.html

If you have the expansions available, make up a bunch of 35 or 40 point ships. Let people choose a ship they want to fly and have a furball. Our group runs them pretty often and has a blast.

I always do 2 X-Wings (PS 2& 4) vs 3 TIE Fighters (PS 1, 3, & 4). Give both sides more than one ship to fly, and teach them the value of PS.