Companion Tickets or other Frequent Flyer Deals
 

So, I have a work trip coming up to Greece, and want to stay on vaca after with my girlfriend. She would be flying in 4 days after me, we would want to return on the same day. (from Boston)

I'm trying to find a way to get her a discounted or free ticket there. the 2 options I can think of are

-companion ticket deals
-redeeming miles for ticket

I've never done a companion deal at all - anyone have any experience to share? does my companion have to fly the exact same days as me? any tips on the best places to go for these deals?

as far as redeeming miles go, I have the following:

110k on Amex Membership Rewards
50k on Delta
50k on American
22k on Continental
25k on US Air

I've tried searching the Delta site for a rewards ticket, but it look like it will cost me 100k miles (flight is at the end of October). I think that's too much...

any other tips/suggestions?