I use Ultra-Pro Semi-Rigid Card Holders for my tickets. I file my tickets in date order - this makes it easy to add new pick-ups into my collection. They're pretty cheap (about $16 per box of 200), they're thin, they keep the tickets firmly centered and they keep the weight down vs. rigid sleeves. I don't collect Eagles tickets (I have the one below because it's from the JFK assassination weekend), but here's an example for you to reference. Larger sizes are available (including a "Tall" version that is the same height).
I keep most of my paper collectibles from postcards to movie posters in mylar sleeves, but I haven't found a small mylar holder I'm happy with yet (Mylar is more likely to shred your fingertips too).
